Why symmetric 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.
Net effect per cash transaction
+0¢
Net effect: $0.00 per thousand cash transactions. Essentially zero, which is what symmetric rounding is designed to do. There is no margin here to capture.
Transactions
100
Rounded up
40
Rounded down
40
Unchanged
20
Per 1,000 cash sales: $0.00
| Price | Exact total | Due in cash | Delta |
|---|---|---|---|
| $0.01 | $0.01 | $0.00 | -1¢ |
| $0.02 | $0.02 | $0.00 | -2¢ |
| $0.03 | $0.03 | $0.05 | +2¢ |
| $0.04 | $0.04 | $0.05 | +1¢ |
| $0.05 | $0.05 | $0.05 | 0¢ |
| $0.06 | $0.06 | $0.05 | -1¢ |
| $0.07 | $0.07 | $0.05 | -2¢ |
| $0.08 | $0.08 | $0.10 | +2¢ |
| $0.09 | $0.09 | $0.10 | +1¢ |
| $0.10 | $0.10 | $0.10 | 0¢ |
| $0.11 | $0.11 | $0.10 | -1¢ |
| $0.12 | $0.12 | $0.10 | -2¢ |
| $0.13 | $0.13 | $0.15 | +2¢ |
| $0.14 | $0.14 | $0.15 | +1¢ |
| $0.15 | $0.15 | $0.15 | 0¢ |
| $0.16 | $0.16 | $0.15 | -1¢ |
| $0.17 | $0.17 | $0.15 | -2¢ |
| $0.18 | $0.18 | $0.20 | +2¢ |
| $0.19 | $0.19 | $0.20 | +1¢ |
| $0.20 | $0.20 | $0.20 | 0¢ |
| $0.21 | $0.21 | $0.20 | -1¢ |
| $0.22 | $0.22 | $0.20 | -2¢ |
| $0.23 | $0.23 | $0.25 | +2¢ |
| $0.24 | $0.24 | $0.25 | +1¢ |
| $0.25 | $0.25 | $0.25 | 0¢ |
| $0.26 | $0.26 | $0.25 | -1¢ |
| $0.27 | $0.27 | $0.25 | -2¢ |
| $0.28 | $0.28 | $0.30 | +2¢ |
| $0.29 | $0.29 | $0.30 | +1¢ |
| $0.30 | $0.30 | $0.30 | 0¢ |
| $0.31 | $0.31 | $0.30 | -1¢ |
| $0.32 | $0.32 | $0.30 | -2¢ |
| $0.33 | $0.33 | $0.35 | +2¢ |
| $0.34 | $0.34 | $0.35 | +1¢ |
| $0.35 | $0.35 | $0.35 | 0¢ |
| $0.36 | $0.36 | $0.35 | -1¢ |
| $0.37 | $0.37 | $0.35 | -2¢ |
| $0.38 | $0.38 | $0.40 | +2¢ |
| $0.39 | $0.39 | $0.40 | +1¢ |
| $0.40 | $0.40 | $0.40 | 0¢ |
Showing the first 40 of 100. The totals above cover all of them.
Run your own numbers
Use the form on the home page, or call the API or MCP server. This page is also available as markdown.
Related examples
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.