Apologize to Gramma.
Get a job, learn how much money that is, and how hard it is to earn that much. I remember stealing when I was little, even not so little. It was more of not having any control of money, no access to earn it. Punishment would only distance the kid from the parent/s I think. He is getting to need to talk to you more and more. I see this as a great ooportunity for you to be able to help him problem solve this issue. Can he help with his "punishment"? Maybe this could also help him see how many people this affects. I would want to be able to somehow earn my own money, and be able to spend it my way (also a great time to talk about savings and charities etc) Perhaps paying Gramma back, and also helping some less fortunate kids with money he can earn by doing EXTRA (beyond family/household expectations) chores. Raking neighbors leaves, shoveling snow...good luck.