@revelette2,
We have junk food tax here in Ontario. Potatoes aren't taxed - they're food. Potato chips are taxed. Orange juice isn't taxed. Orange soda is taxed - it's junk. One muffin is taxed (snack/junk), six muffins in a package aren't (that's probably my favourite weird one).
Seemed weird when it first came out. Now I think it makes sense. It's like taxing booze/cigarettes/other things that aren't good for you.