If you were going for an office position I would recommend:
Single breasted Suit. Dress black shoes (preferable with laces). Matching shoes with belt. Suit should be dark (navy, black, charcoal). WHITE dress shirt (no-button down collar). Socks should match suit color. Conservative tie (preferably striped- navy and maroon diagonal stripe is the most conservative, or solid, checkered tie. NO flowery, or bright neon ties).
Tower Records?- You still want to be decent. NO sneakers. Nice clean jeans if you don't have khakis (preferably ironed). White dress shirt with khakis is good but if not jeans are okay too. If you don't have a white shirt, any button down shirt (solid color or simple pattern). NO SHORT SLEEVED SHIRTS.
Pretend you are going to meet your girlfriend's family for the first time on a Thanksgiving dinner and you can't go wrong. It is ALL about FIRST impression.
Just DON'T wear a t-shirt, raggedy sneakers and jeans. If you don't have any of the above, go to Wal-Mart and you can get the whole ensemble for under $40 ($20 shirt, $20 pants) and you will look brand new. Trust me, I have shopped at TJ Maxx, Ross, Wal-Mart and even the Good Will store and you would be VERY surprised at the deals you get.
SHAVE and BATHE and don't forget the deodorant. NO jewerly (chains, bracelets, bunch of rings). Neat hair counts! Cut your finger nails. NO SMOKING right before the interview. NO soda (burp), ABSOLUTELY NO GUM chewing, mouth wash... They all seem basic but you would be surprised what people don't know or forget.
You are dealing with the public and although Tower Records is a bit more Rock-'N'-Roll, you still want to make a good impression on your interview and AFTER you get the job, you can let loose.
GOOD LUCK and SELL yourself. Think POSITIVE and be CONFIDENT.
HOPE YOU GET THE JOB!!! (One last thing, try not to ask TOO much about holidays, benefits, money...they will volunteer this information. And, try to be interested in the job, ask questions...)