How sales tax moves the rounding band
Tax decides which nickel a price lands on, so the band of prices that settle to the same cash amount moves with the rate.
Free to take
3¢
5 list prices between $19.98 and $20.02 all settle to $21.65 in cash at 8.25% tax. Listing at $20.02 instead of $19.99 collects exactly the same from cash customers and 3¢ more from every card customer. That is the only genuinely free move rounding offers, it is worth 3¢, and it evaporates if the tax rate changes.
Every nearby price, and what it settles to in cash
| List price | Exact total | Due in cash | Rounding |
|---|---|---|---|
| $19.94 | $21.59 | $21.60 | +1¢ |
| $19.95 | $21.60 | $21.60 | 0¢ |
| $19.96 | $21.61 | $21.60 | -1¢ |
| $19.97 | $21.62 | $21.60 | -2¢ |
| $19.98 | $21.63 | $21.65 | +2¢ |
| $19.99yours | $21.64 | $21.65 | +1¢ |
| $20.00 | $21.65 | $21.65 | 0¢ |
| $20.01 | $21.66 | $21.65 | -1¢ |
| $20.02best | $21.67 | $21.65 | -2¢ |
| $20.03 | $21.68 | $21.70 | +2¢ |
| $20.04 | $21.69 | $21.70 | +1¢ |
The shaded rows all settle to the same cash amount. Within that band the cash collected is identical, so the highest list price in it is strictly better — the difference comes from card customers, who pay the listed price to the cent.
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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.