The interview processes consisted of about 2.5 interviews. First, there was a phone call from their HR rep. She asked me a few general questions about my availability and interest in the position, and then we set up a time for a more formal phone interview. This phone interview happened about two days later. I called her and she asked me detailed questions about my work experience and asked me questions about working with others and past experiences, etc. At the end, she set up a formal in-person interview with the manager of the store I was applying to.
That interview was very easy and only lasted about 10-15 minutes. She asked me questions about my availability and my ability to work with customers and operate a register. I was offered the job on the spot.
I would suggest wearing something "business casual" to the interview. Not a dress or a full suit and tie, but rather dress pants and a nice shirt, or a skirt with tights and a nice shirt. Definitely no yoga leggings, girls- this a formal interview. I wore black dress pants, a silk shirt, and a cardigan.