Quit it.
I assume u r 20,21 and making 15$/hr.That's good. You should be satisfied for now. You r just a student.
Stealing in itself is a bad deed. Yes,we all want more money,there is never a limit to it.For that either u work hard and make more money or look for another job but stealing is lowering yourself in your own eyes as well as others if u ever get caught(u might be....Paap dhuri bata karauchha). Honesty and hard work as well as self control will take you a long way in your life.Even if u see others doing it,u don't do it. You know what ,in our life we need self control too.It helps us a lot.
Hope u'll stop doing it and choose a right path .Ultimately,that's the only thing that will give you peace of mind and happiness in your life :-)
My two cents..........