Round once or round every shift?

Formatting and rounding answer different questions

Formatting makes a number readable. Rounding changes it according to a rule. A decimal display might show 0.33 for a 20-minute duration, but the stored record can still be exactly 20 minutes. Do not replace the original record with a shortened display and then describe the resulting difference as ordinary calculation error.

Name the complete rule

“Round to fifteen minutes” leaves several questions unanswered. Does the rule choose the nearest interval, always round down or always round up? How are halfway values handled? Is it applied to each shift, each day’s net total or the complete reporting period? Those are different instructions, even if they mention the same interval.

• Keep original start, end and break values.
• Choose the increment and direction explicitly.
• Choose one application level.
• Compare exact and rounded totals before applying the setting.

A small counterexample

Consider two independent eight-minute shifts on the same day and a nearest-fifteen-minutes rule. Rounding each shift gives fifteen minutes twice, for a thirty-minute sum. Adding the original shifts first gives sixteen minutes; rounding that daily total gives fifteen minutes. The difference comes from the level, not a different source record.

A familiar shift example

A shift from 09:02 to 17:28 spans 506 minutes. Subtract a 30-minute unpaid break to get 476 minutes, or 07:56. Applying nearest fifteen minutes once to that daily net total gives 480 minutes, or 08:00, a change of four minutes. It does not move the original clock-in or clock-out times.

Keep the boundary clear

MinuteFolio starts with rounding off. Its optional rules are user choices for a calculation preview, not legal payroll advice. If another process has required rounding instructions, review those instructions independently. When sharing a rounded report, keep the chosen rule visible and retain the exact project backup so the original record can still be inspected.

Sources and method

• NIST SP 330, Section 4, Table 8Time-unit definitions only; not a payroll authority or product endorsement.
• Original worked calculationSynthetic example data, explicit input rules and direct integer-minute arithmetic.