pricing issue

Hi folks,

I have an issue regarding pricing

let us say my basic price pr00 is 100 rupees

and 1st discount condition type is 10%,

and 2nd discount condition type is 10%

and 3 rd discount condition type is again 10 %

NOW 4 TH discount condition type is mrp-1st discount is my 4 th discount

now last my 5 th conditio type that is cash discount is on my

mrp- 2nd -3rd that should be my selling price

what ever the selling price on that am adding tax is 20 rs how can i configure all this things in my pricing procedure.

Thanks In advance

Rack29