Prices for variations

[cjarmain]

I have a shopping cart that has products with either box sizes (3 pack, 6 pack) or bag sizes (5kg, 10kg). I have set them up using variations however i want the sale price to be the price of the product not the difference between the base price and the variation i.e Base price for 3 pack = $20, price for 6 pack is +$15 NOT 6 pack is $35.
I am told this is a feature of variations and can not be changed, however i need a solution if anyone has one.