Discounts by specified price, not percentage

I'm not seeing info specific to this, but maybe it's easy to address. I have a client with an existing database of product. Within their primary category of product (boxes of moulding), they have different prices based upon the total number of boxes you purchase. I see a straight forward way in which to set a rule for a discount based upon the box total, but it appears that allows me to set a percentage discount. Rather than a percentage, I need it to use column:PriceA (unique to each product) if the order is 1 to 4 boxes, column:PriceB (once again unique to each product) if the order total is 5 to 8, and so on.

Is there a relatively simple way to do that rather than a percentage discount?

you will need to create a calculation for this.

on the calculation tab create a new calculation as:

realPrice:

((abs([Quantity] >= 1 && [Quantity] <= 4):[PriceA]:0) + (abs([Quantity] >= 5 && [Quantity] <= 8):[PriceB]:0))

you can keep building this up with the various quantity breaks. you will also need to edit the Total Price calculation to:

((abs([Quantity] >= 1 && [Quantity] <= 4):[PriceA]:0) + (abs([Quantity] >= 5 && [Quantity] <= 8):[PriceB]:0)) * [Quantity]

In the cart display, you will want to change the Price to use the realPrice calculation, and also in the code that passes the order information to the gateway, set the item price to use the realPrice.

Thanks Jason. This job is still in the quoting stage, so it will be a bit before I tackle this problem, but it doesn't appear extraordinarily difficult to solve. That's what I need for now.