Jonathan Dix, who taught at The Business Academy in Bexley, Kent, was found guilty of unacceptable professional conduct by the General Teaching Council.
In March 2005 Mr Dix, from Swanley, stole pound;240 from a till and was given a police caution for theft.
He said in a written statement that at the time of the incident his wife and step-daughter had started university and his supermarket job helped with costs. "There is not a day that goes by when I do not regret what I did," he said.
Mr Dix said the academy wrote him a letter of support saying the theft should have no bearing on his teaching career.
He began at the academy in 2002. He left earlier this term and now is in a non-teaching job.
The committee took his regret and the school's letter into account when issuing the suspension.