How do you handle the moment your invoice reader isn't sure about a field?

For anyone who processes supplier invoices for a living: the part that eats the evening isn't understanding the invoice, it's retyping it. Same fields, ten different layouts, and the totals don't always match the lines.

Two rules I ended up with:

1) Never let the tool fill a field it isn't sure about. A guessed total looks exactly like a correct total until the accountant finds it three weeks later. An empty field with a flag costs ten seconds.

2) The biggest number on a receipt isn't necessarily the total. I once saw a reading come back with 190.00 while the register had printed 832.50 — 190 was one line item with a discount. The fiscal QR code holds the total the register itself signed.

Curious how others do it: leave the field blank and flag it, let it guess and fix later, or block the document until a human confirms? And do you reconcile the total against something independent, or trust the extraction?