I have following problem:
Salesmen give x% in discount
If discount % is between 0-4% he gets 25% bonus
If dscount is 5-9% he gets 20%
If discount is 10-14% he gets 15%
If discount is 15-20% he gets 5%
If discount is 20% he gets 0%

How can I make function for this.

Can someone help
Thanks
Bogi