Blank discounts using price manager

I use zen cart version 1.3.9f. I recently set up blank discount for products by using the price manager of the zen cart. It is working really great.

I wonder if there is a way to count all the products of a single category to give multiple quantity discounts. Specifically I would like to count any item within a category as eligible for multiple quantity discount. If a customer buys item 1 from category A and item 2 from category A I would like to give him a discount for buying two products.

I could not find any information in the posts on how to do it?Does it require custom code or can I use the existing feature to do this? Any clue or guidance would be appreciated.

The native quantity discounts only discounts a single product. To mix and match within a category, you can use the Quantity Discounts contribution in the free software add ons.