To increase pricing based on percent just enter the percentage and a percent sign in the amount box 
. So if for example you want to increase by 2.5% enter 1.025%. This will calculate the current price times 1.025.
When updating by percent in order not to get decimal amounts you can use the round to nearest 
option. If you want to round to nearest dollar put a one, nearest 10 enter 10 and so forth.
