# Penny Rounding

Round a cash transaction the way the post-penny rules actually work: on the final total, after tax, for cash payments only. Shows the exact total alongside the rounded one, names the rule being applied, and computes the real expected rounding effect across a price list — which is close to zero, not the free margin it is widely assumed to be.

**Not for:** Not legal, tax, or accounting advice. Federal rounding legislation was not enacted as of September 2026, state law varies and is changing quickly, and a rounding practice that is lawful in one state may not be in another. This computes arithmetic under a rule you select; it does not tell you which rule applies to your business. Check your own state law and your own tax authority.

## The rule

| Final digit of the total | Rounds |
| --- | --- |
| 1, 2 | down |
| 3, 4 | up |
| 6, 7 | down |
| 8, 9 | up |
| 0, 5 | unchanged |

## The four things that are usually wrong

1. **Cash only.** Card, EFT, and gift-card payments are still priced to the cent.
2. **The total, not each item.** Five items at $0.99 come to $4.95 — already a nickel.
3. **After tax.** Tax is computed on the exact subtotal; rounding happens last.
4. **It is not free money.** Symmetric rounding nets to approximately zero. The one genuinely free move is worth at most 4¢, and it is not the obvious one.

## Status of the law

- Penny production ended 2025-11-12.
- Existing pennies remain legal tender indefinitely. This is not demonetisation.
- Common Cents Act (H.R.3074 / S.1525): House 2026-07-14, Senate 2026-08-07. **Not enacted** — each chamber passed a different bill number, so the House must still pass the Senate version. The text is permissive, not mandatory.
- Verified 2026-09-04. This is moving; check before relying on it.

### States with enacted frameworks

| State | Bill | What it does |
| --- | --- | --- |
| Arizona | AZ HB 2930 | Sets rounding methods for cash payments, and requires that rounding happen after sales tax is calculated and applied. |
| Indiana | IN SB 243 | Canadian-style rounding to the nearest nickel for retail transactions. Separately requires that cash payments of state and local TAXES always round DOWN — an asymmetry that does not apply to ordinary retail sales. |
| New Mexico | NM HB 291 | Authorises the revenue department to allow or require taxes and motor vehicle fees to be rounded to the nearest nickel. |
| Tennessee | TN HB 1744 | Price rounding for cash payments, applied after tax is calculated. |
| Utah | UT HB 597 | Establishes a framework for how retailers handle cash transactions without pennies. |

This tool does not know where you are and will not tell you which rule applies to you.

## Surfaces

- HTML: `https://penny-rounding.gumballtools.com`
- Markdown: same URLs with `Accept: text/markdown` or `?format=md`
- JSON API: `https://penny-rounding.gumballtools.com/api/v1/settle`, `/api/v1/impact`, `/api/v1/price-band`
- OpenAPI: `https://penny-rounding.gumballtools.com/.well-known/openapi.json`
- MCP: `https://penny-rounding.gumballtools.com/api/mcp`

Amounts are integer cents internally. A numeric amount is read as CENTS and a string as dollars, so `1999` and `"19.99"` are the same amount.

## Worked examples

- [What does $4.37 round to in cash?](https://penny-rounding.gumballtools.com/rounding/what-does-4-37-round-to) — $4.35. It ends in 7, and 1, 2, 6 and 7 round down. The digit is the whole rule.
- [The cash rounding rules, in one table](https://penny-rounding.gumballtools.com/rounding/cash-rounding-rules) — Final digit 1, 2, 6 or 7 rounds down; 3, 4, 8 or 9 rounds up; 0 and 5 stand. Nothing else to memorise.
- [Round after tax, never before](https://penny-rounding.gumballtools.com/rounding/round-after-tax-not-before) — Rounding the subtotal first changes the tax owed and puts the register out of step with the tax authority. Here is the same sale done both ways.
- [Round the total, not each item](https://penny-rounding.gumballtools.com/rounding/round-the-total-not-each-item) — Five items at $0.99 come to $4.95 — already a nickel, no rounding at all. Rounding each item first would collect $5.00.
- [Why cash and card come to different amounts](https://penny-rounding.gumballtools.com/rounding/cash-vs-card-same-basket) — The same basket, paid two ways. Card is charged to the cent; only cash is rounded. This is intended behaviour, not a bug in the register.
- [Does rounding make retailers money?](https://penny-rounding.gumballtools.com/rounding/does-cash-rounding-make-money) — No. Symmetric rounding nets to essentially zero — here it is, computed over a real price list rather than asserted.
- [Why symmetric rounding nets to zero](https://penny-rounding.gumballtools.com/rounding/rounding-nets-to-zero) — Across evenly spread totals the ups and downs cancel exactly. That is not a coincidence; it is why this rule was chosen.
- [What rounding everything up would be worth](https://penny-rounding.gumballtools.com/rounding/what-rounding-everything-up-would-be-worth) — Two cents a cash sale. Quantified here because the number is the argument — and no jurisdiction has adopted it for retail.
- [The rule that always rounds down](https://penny-rounding.gumballtools.com/rounding/tax-payments-that-round-down) — Indiana requires cash payments of state and local taxes to round down. It is a narrow provision about paying tax, not a retail rule.
- [Is there a price that rounds in my favour?](https://penny-rounding.gumballtools.com/rounding/pricing-to-the-nickel) — There is one free move, and it is worth four cents. It is not the one most people go looking for.
- [How sales tax moves the rounding band](https://penny-rounding.gumballtools.com/rounding/price-band-with-sales-tax) — Tax decides which nickel a price lands on, so the band of prices that settle to the same cash amount moves with the rate.
- [What the penny phase-out does to .99 pricing](https://penny-rounding.gumballtools.com/rounding/ninety-nine-cent-pricing) — A $0.99 item still lists at $0.99 and still shows $0.99 on a card. Only the cash total moves, and only at the end.