Stuck again!

I am using the following code to produce an error message when the Quantity for specific product numbers (listed below) is up to 499 users AND when the discount exceeds 40%. What I'd like to do is expand this code to include a number of quantity ranges, say 500-999, 1000-1500 etc, where the discount  (against the same product codes) should not exceed 45%, 50%, 60%, respectively.

Is there a way to do this in one code string rather than create unique validation rules? Here's what I am using...it works  for up to 499 users, and up to 40% discount:

AND(
OR
(Product2.ProductCode= "EN-P-MPS-100",
Product2.ProductCode= "EN-P-PC-100",Product2.ProductCode= "EN-P-CP-100",Product2.ProductCode= "EN-P-IP-100",Product2.ProductCode= "EN-P-AW-100",Product2.ProductCode= "EN-P-AWS-100",Product2.ProductCode= "EN-P-CCE-110",Product2.ProductCode= "EN-P-OC-100",Product2.ProductCode= "GE-P-MPS-100",Product2.ProductCode= "GE-P-PC-100",Product2.ProductCode= "GE-P-OC-100",Product2.ProductCode= "EN-P-ICM-200",Product2.ProductCode= "EN-P-SPPM-200",Product2.ProductCode= "EN-P-MISCA-300",Product2.ProductCode= "EN-P-MIBCA-310",Product2.ProductCode= "EN-P-MISCIT-320"),
AND(
(Quantity<= 499)),  Discount  > 0.40)

Put another way, how do I introduce quantity ranges, each with a unique discount % against the same product codes in the same validation rule?

Thanks in advance for the help!