when you're in the interview, make sure you claim your only negative aspect is that you're sometimes a perfectionist and you like things to be neat. you won't quit until the jobs done and you like looking back at what you have accomplished. those are all key.
my mashups ❶ http://soundcloud.com/gotta-mash-em-all
album download here ❷ http://www.mediafire.com/?1dzyy4q1qwb
to be honest. i worked at a grocery store and they will probably only hire you if they need you and have not too many other interviewees. what you're wearing probably wont matter a whole lot but if it makes you more confident just wear some slacks and a white button down tucked in. no need for a tie. its a fucking grocery store.