Attributes Qty Price Discount on Mixed Items

OK, so it seems that the Attributes Qty Price Discount does not take into account the total number of items in the cart> My example:

We wholesale printed t-shirts. Each product is a design with 2 attributes - size and shirt color. Customers may purchase a design on an assortment of sizes and shirt colors, but the shirt colors have separate qty discounts.

The price manager Quantity Discount doesn't work in this case because the qty prices for white break down differently from qty prices for black. Attribute Qty Prices works almost exactly how we need EXCEPT it doesn't tally the total number of items ordered, it counts the line item qty to determine the discount level:

example qty breaks:
50 - 8.00 black; 8.00 white
100 - 7.50 black; 7.30 white
150+ - 7.00 black; 6.75 white

Sample Order using the current cart logic:
design1 - 50 Black, Lrg @ 8.00/shirt
design1 - 50 Black, Med @ 8.00/shirt
design1 - 100 Black, Sm @ 7.50/shirt
design1 - 125 White, Med @ 7.30/shirt

But this is not what we want the cart to do, we want the cart to see that there are 325 shirts and thus the price per shirt should be using the 3rd tier:
50 Black, Lrg @ 7.00/shirt
50 Black, Med @7.00/shirt
100 Black, Sm @ 7.00/shirt
125 White, Med @ 6.75/shirt

It gets more complex because the client wants to allow them to mix the colors to get their total and I am pretty sure Attribute Qty Discount was not intended to handle that.

So, any ideas on ways to improve the situation? We would pay for a developer to add this functionality.
Thanks!
Alane