Tax on potato chips?

I have noticed that some gas stations charge a sales tax for chips and other pre-packeged snacks while others do not. Why is that?
Answer:    Because, it isn't a necessary food, like milk, meat, and other things need for nourishment. Not eating potato chips will not in any way stop you from growing or cause you to starve to death, unless by chance that is the only thing you eat, but then you'll have worse problems than starvation.
I don't think that they should be.
You don't charge tax on food products unless they are prepared there. ie: subs, pizzas, fries,
u r paying tax one way or another. some may have the price including tax on the package. others add it when you pay. trust me, they are all having you pay tax otherwise the irs would be on them like white on rice.

In response to the first person, it depends on what state u live in.
Wisconsin doesn't add tax to grocery items, but here in Illinois not only do you pay state tax, you also pay a county tax.
it depends on the state. It is probably because it is a convience or luxury item. You do not need potatoe chips to live. There are many other items that are needed more than that.
It varies from state to state and depends on the ingredients.
I think this is determined by what county you are in, and what you're buying. I.E. you can tax a prepared sandwich, but you can't tax lunch meat.
It depends on the state - different states tax different items. Some tax all food, some tax what they consider luxury food, and some don't tax food at all. Theoretically the taxation should be the same for an entire state unless a munipality also has a sales tax, which is not unusual. You could contact the state department of taxation and ask, then also the municipality, but that might not be worth the effort. Years ago when I moved to PA, I bought identical pairs of tennis shoes for two of my boys, one at a discount store, one at a sports store, the sports store charged tax, the discount store didn't, I tried calling the state and never really did get any satisfaction since that that time basic clothing was not taxable in PA, sports clothing was.
Sales tax is a state matter. In Illinois, chips are considered food and taxed at 2% if sold in a grocery store. However, food items sold in gas stations, where it is considered incidental, are treated the same as food sold in restaurants and taxed at the full tax rate, which in Chicago would be 9%. Some places don't show the tax separately, and pay the state as though the tax was included in the selling price.