Sales Discounts for different types of Items

I have one requirement that, I have to give sales discount to a group of items. That too qty based discount. Means i want to give discount to x,y,z items and if x item qty is more than 10 items 10% shloud apply, y item qty is more than 15 items then 8% discount should apply, z item qty is more than 30 then 20 % discount should apply. Can you give assistance on this any setups need to configure or any discount agreement journal need to post. Plz give solution for this this is my client urgent requirement now. Thanks in advance