How to have 2 different price precision?

Default in all categories the price is configured by 2 decimals.

example PRODUCT 1: 150,34

In one particular category there is need to have 3 decimals becouse the prices per product is very low and the quantity usually the costumers order is more than 10000.

So we loose much money from the rounding!

I am searching for applying 3 decimals in only one category and not in the whole eshop.

Any hints or ideas where i can to search for the code?

thanks for any help!