<human>: Summarize the given text in a few sentences.

From July 2006-March 2008 I was working at Best Buy. The reason I got fired was for "Time Fraud." The occurrence happened on a day where their computer system was down, therefore making clocking In/Out impossible. So we had to manually fill in our times. I went to lunch, ate, and went back to the floor. I put down on the form that I took a 30min lunch. Somebody was watching and they had the managers check the cameras and I had actually taken a 40min lunch.
They reported it to HR and a few days later, the manager brought it to my attention. I honestly didn't know and offered to fill a new form out with the correct times. He said it was too late and that he had to let me go. He said the reason was because that I had stolen from the company. Not a physical product, but time. No warnings, and no prior write ups. My attendance was perfect. Never late, never called in sick.
I had an interview a few months ago and this came up. I told the truth and the interviewer grilled me and didn't believe that it was an honest mistake. So, for the next one, how honest should I be?
<bot>: Accidentally took a 40min lunch but said I took a 30min lunch. Fired. No warning, no prior incident.