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.
We will go cheap. 15 dollars. Now lets look at what your time and your buddies time is worth,lets say 15 dollars an hour for each minimum 2 hours so there is 60 dollars. I know alot of you make more than that or at least that is what you tell the delivery driver when he is running behind.