Accurate Row-Level Price Calculations for Low Unit Prices

We improved product row price calculations to handle edge cases with very small unit prices, where imported order rows could show incorrect rounded row totals.

Order totals and tax calculations were always correct, but the per-row totals displayed on invoices could be rounded incorrectly. As a result, affected invoices now show corrected row amounts.

If you notice any regression, please create a ticket so we can investigate.