separate row per discount level in order invoice

[daleto]

Hi

I have created 3 different price sets for a product.
If the quantity is 0-99; than 0% discount should be given
For the quantity that are between 100 and 499, 10% should be given
For the quantity that are over 500, 20% should be given.

I tried this by creating a tax & calculation rule,
but could not make this to work in the way how I want it.

Example:
Let's say that a customer want to order 1500 of this product, and the unit price is 1€
Than I want the invoice / order to have 3 lines mentioning the different discount levels
Line 1: product X, quantity 99, unit price 1€,discount 0€, total 99€
Line 2: product X,  quantity 399, unit price 1€, discount 39.9€, total 349,1€
Line 3: product X,  quantity 1000, unit price 1€, discount 200€, total 800€

Or something similar.
Why is this important?
Because if we have a flat discount where customers enter 500 as quantity,
it will be much cheaper than a quantity of 499.

Please let me know how this can be implemented

Regards Tomas