How do I round off time entries while invoicing them?

To configure round off preference for your time entries:

Go to Settings by clicking the Gear icon in the top right corner.
Select Timesheet under General in the Module Settings pane.
You can change the round off preference of the time entries you record as follows: Round up to, Don’t round off, Round down to, and Round to nearest.

Note: If you wish to apply the round off preference to the timesheet details report, you can enable the option Apply the Round Off Time preference to the Timesheet Details report.