We often come across Buy One Get One (BOGO) offers these days like Buy toothpaste and get Toothbrush free or Buy 5 soaps and get 10 % off or Buy 2 kg sugar and get ½ kg free etc etc . To configure something like this in siebel we can go for the Aggregate Discounts.

Aggregate Volume Discount
We have seen in the Volume Discount article that this type of discount works line item by line item. with some customers this could be a debate and some would prefer to change this behaviour:
Volume Discount should be calculated based on all instances of the same product (Quantity aggregation).
Fortunately the PSP architecture shipped with Siebel 7.8 and above introduces a new pricing engine. Since price calculations are done in Workflows and Business Services, we can change them.

Volume Discount
Volume Discount is probably the easier discount to understand and to implement.The idea is to give a discount if you buy more of the same product. Example:

If you buy 4 products ABC, you get 3%
If you buy 5 products ABC, you get 3.5%
If you buy more than 6 products ABC, you get 4%

You add product ABC to the Quote/Order, you update the Qty field to a value of 4 or greater and you will see your volume discount applied.