From experience, those differences surface during stock taking. Amd most companies are really bad at that. And if they surfacey they are corrected by inventors adjustments (in unit of measure, not value, which is a differwnt can of worms). As long as those adjustments aren't to extreme, nobody really cares.

A good accountant so will sooner or later investigate those rounding errors, as they will show up somewhere ultimately. And a general policy of rounding in one direction is the last thing you want an auditor to find.