You'll have to decide when and how to round. Keeping individual billing items at high precision and rounding after summing them up can work; defining and docume

You'll have to decide when and how to round. Keeping individual billing items at high precision and rounding after summing them up can work; defining and documenting a rounding policy (or complying with whatever's legally required in your jurisdiction/domain) and rounding each individual billed item can as well.