Cash Discount in sales orders if customer paid payment in advance

Hai,

If sales order created againest Advance paymants additional cash discount 2% needs to be provided in sales order selling price.

Example

Customer - X
Customer have credit balance Rs.10000
If sales order going to create for this customer up to order value Rs.10000 additional cash discount 2% needs to be
provided in sales order selling price.

If anyone have idea about the above said requirment kindly share the details is useful for us.

Regards,
Shiva.