Most Helpful Guy
One of the problems with open shoes is that while they look stylish, they also offer little to no protection against injury while working in retail. As you'll be dealing with many different objects, it is not commonly accepted to have open shoes in such an environment at all. For your own safety, as well as you looking more professional, I'd take some closed shoes instead.
Most Helpful Girl
I would never suggest you wear any type of open toed shoe to an job interview of any sort. It's just an hour or so, and I'm guessing you'll be indoors when this interview takes place, so just deal. It's never good to go in with the attitude, "it's just retail," either, because unless you know the person in hiring, they may expect the same standards of interview dress as most other jobs especially if their staff are expected to wear closed toed shoes on the job (usually a safety regulation for most jobs anyway).