This is what I want to do, I hope I can explain this right....

I want to Calculate a percentage only if it meets certain criteria.

I want to calculate a 2% surcharge only on a particular item, and 0 for the others.
For example

I have a list of different items such as: candy, soda, dolls, bears, sweaters, toy cars. I want to add a surcharge of 2% only to the candy and the soda, but not to the others. How do I build this expression? HELP!

I've already tried the expression builder, and since I don't know what the heck I'm doing, I'm not an expert, so whatever I'm doing is not working.