Reporting part-time earnings while on benefits - what worked for you?

I picked up part-time shifts as a payroll clerk and I am confused about how to report them. I would rather hear the honest version than the polite one. The form asks for gross earnings, which I do not see until later. Who can I ask without risking my claim?

Report honestly and keep your stubs. An honest small error is much easier to fix than a missing report.