This. An important property of tax calculations is being consistently reproducible. In the context of an audit, the calculations don’t need to be accurate per se just precise.

I have a formative story where a large industrial company was counting things for tax purposes using my software. Given the same data and same binary, the count was off by one depending on if it was running on Intel or AMD CPUs. They didn’t care so much what the count was, they just needed it to be the same value at all times in all places so they could defend it in an audit.

The inability to consistently reproduce the value was a bigger liability for tax purposes than small variances in accuracy that fell out of the process.