Much junk food is taxed in many states in the sense that it is subject to sales taxes that regular foodstuffs aren't. Where I live, if I buy a loaf of bread and a Reese's cup there's no sales tax on the bread but 7.5% on the Reese's cup.

(However, if I buy a "take-home pack" of 12 Reese's cups they're not taxable. Same with Twinkies. One twinkie, taxable. Box of Twinkies, nontaxable. Go figure.)

Bruce