He should call. Doing stuff like that is technically illegal. Tbh; as cruel as it sounds, that kid should lose his job over it.'
edit: I would also contact your credit card company... even though its $3 and seems like extra effort -
I know it's the "right" thing to do - but everybody has done stupid things as a kid (obviously we're assuming this was a teenager working the counter, not an adult - that'd be a whole different story). $3 isn't worth it, in my mind.