I'm not sure it's the other way with VAT, as I said it's been many years and the rules may well have changed multiple times.

The key, though, is that with taxes, if at all unsure you've got the rules right, the safest option is to round in the tax offices favour.

It's in general a lot less painful to explain an overpayment than underpayment if something is broken.

Of course, better yet, get it right.