Asef Azimi, of Stuart Road in Corby, will face no further punishment if he doesn't commit any more crimes after being given a slap on the wrist by magistrates.
On March 27 this year Azimi, 35, was at the Joules distribution centre in Saxon Way West when he pilfered the charity box.
It is not known how much money was in it.
Last week magistrates in Northampton handed him a 12-month conditional discharge, meaning he won't be sentenced for it unless he commits a crime in the next year.
Azimi, who admitted theft, must pay compensation of just £20.
He will not have to pay any prosecution costs because of his limited means.