Buy a bunch of albums you're into. See if he has any reactions like "Hey i like this band." Turn it into a conversation. Get a little flirty. Then, right as youre about to leave, put an envelope on the counter containing a piece of toast. He'll get the message.
If he works at a music store, he must like music. Write a song and learn how to play an acoustic. If that fails, tell him you'll have sex with him but only if he takes you out to dinner first. That'll win him over.