I have short changed hundreds if not thousands

I am a cashier at a very well known department store. In the four years I have worked there I have shortchanged hundreds of people. A dollar here and there, sometimes even a five. I used to have problems counting change but as I got better, I realized I could still short change people and keep the money myself while playing the "oops I didn't count it right?". It pays for my smokes and gives me some drinkng money.
I don't feel that guilty about it. The people are there spending money anyway. What's a few dollars here and there?

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