List -> Account -> Currencies is where you can go and set up currencies and their precision.. Since you are using $ (USD) there is no concept of a half cent so 0 or 2 decimal places for amount is all you're going to get. The Rate however, can be X number of decimal places. If you don't want native Quantity * Rate = 0/2 decimal precision, you'll need to do this calculation yourself based on the rate to get your amount (1 * item rate of 14.876) = amount of 14.876 (which will get rounded to 2 decimal places once amount is set) and set the tax based off YOUR calculated amount of 14.876 * 21% and let netsuite handle the rest.