I am trying to set up 2 different prices for different quantities of the same product. I have a juice flavor 15 ml priced @ 8.00 with a 6% tax which works properly. I need to add a 30 ml @ 13.50 + tax. I either get 13.50 and no tax applied or 8.00 with tax. I have used the combination generator for drop down but don't know how to change the price for different quantities.