Reading the chart
The 7-minute rule is just "round to the nearest quarter hour": punches 1–7 minutes past a quarter mark round back to it, and 8 or more minutes past round forward to the next one. It cuts both ways — clocking in at 8:07 gains you 7 paid minutes, clocking in at 8:08 costs you 7. Over a legal, neutral policy those swings should wash out.
The other rounding intervals
Quarter-hour (15-minute) rounding is the most common, but systems also round to 6 minutes (tenths of an hour — a 9:04 punch records as 9.1 hours) and 5 minutes. The split point is always half the interval: 3 minutes for 6-minute rounding, 2.5 for 5-minute. To round a specific punch at any interval, use the interactive time clock rounding calculator.
When rounding crosses the line
Rounding must be neutral in practice. Red flags: a system that rounds clock-ins up but clock-outs down, supervisors editing punches after the fact, or grace periods applied only in the employer's favor. If you suspect drift, compare a few weeks of actual punches against paid hours with the paycheck hours verifier — and keep your own record in the time card calculator, which never rounds unless you ask it to.