How to define the price break modifier in advanced pricing

Hi,

We need to define the price break modifier and our business scenarious are mentioned below.

Qty Range       Discount

Up to 350       - 1.50

351 to 450      - 2

451 to 550      - 2.50

550 Above     - 3

If the order quantity is 560, system should calculate the discount as like below.

List price will be Rs.40

Qty   Discount   Discount Value

350     1.5              525

100        2              200

100      2.5             250

10           3             30

560                       1005

Avg Discount is    1.79

(Total Discount Value/Total Qty) i.e 1005/560

Net selling price will be 38.21 (i.e 40 - 1.79)

How to configure this functionality in the advanced pricing modifiers.

Anybody have idea/document kindly share the same it will be helpful to us.

Regards,

Shiva.