Add Quantity discounts to products in MarketPress

Please add a section on a product so you can program quantity discounts as both procentage and specific pricing for a range of specific numbers ordered.

Like this:

Below quantity Price %
10 10
100 9
250 8.50
500 8
1000 7.50
1000000 7

This would really help the usability of the plugin - instead of fiddeling with coding in the shipping module...