Sales tax is percent
a)increase
b)decrease
discount is percent
a)increase
b)decrease
tip is percent
a)increase
b)decrease

Sales Tax would be considered a) percent increase, because it is an added amount onto the total. Discount would be considered b) percent decrease, because it takes a certain amount off of your total. Tip would be considered a) percent increase, because similar to sales tax, you must add it on to your total.

The Sales Tax is percent: Increase because it is going upward and you're adding on 

Discount is percent:  Decrease because it is downward and because you're taking a certain amount off 

Tip  is percent : Increase because you're giving  in and it kind of like the "Sales Tax" 

Therefore, your answers would have to be: Increase,Decrease, and Increase :)