I think it's only fair that I steal from a store that overcharged me
Why do you think they overcharged you?
I don't know, but I've been working in a store ever since I was a child. So, I recognized it immediately.
That doesn't answer my question. Even if you did get overcharged, you should never steal. There are legal and moral consequences to doing that.
You're right, but this overcharge is so bad I'm going to steal anyways.
You could end up in jail for stealing, and the overcharge will not be accepted as an excuse. Try contacting management to see if they can help you fix it instead.