Why the interviewer is asking this question: The interviewer is asking to align expectations for the role with your long-term expectations. While interviewers typically want solid alignment on near term (i.e. under 5 years) expectations, more latitude can and will be given for longer term goals.
If they don't want to give benefits to stocker and cashiers they should have part time hours and paid $17.50 per hour no benefits. Also how many teenagers would like a parttime job from 3 pm until 7pm and maybe get the pay they give their cashiers $8 -9 an hour.
It depends a lot on where you work, or if you work solo.   Answer   With 0 experience and no certs, I started at $12/hr, and within a year got bumped 25% to $15/hr.