My eighth-grade math teacher (public school) stated that if you are accidentally given too much change at the cash register —and you see it and don’t correct the error by returning the overage— then you are stealing.
I am surprised at some of the responses on this thread.
Then the bozo who hired the employee who over-changed me owes me money for giving his employee on-the-job training. I'm not stealing. I charge for math tutoring.