Correct. Precision must be parameterized for every variable. 2 is the most commonly used value (for money), but not the only reasonable one. And rounding needs

Correct. Precision must be parameterized for every variable. 2 is the most commonly used value (for money), but not the only reasonable one. And rounding needs to be done at certain steps but not a others. Typically internal calculations are expected to be done with maximum precision, and every time you have an item visible to the customer you round. Often to full cents, but there are cases where you show a fixed number of decimal cents even to the customer. I doubt that cases where you show maximum precision to a customer are common.