osCommerce store not set-up for tax?

We have just implemented an update for osCommerce, Zen and CRE Loaded store owners.

A few of our customers had not configured their websites to charge VAT - but they were registered.

So we have put in an option to override the site's tax settings, and treat the order value as including VAT.

When the orders are imported, we automatically calculate the VAT component and insert it in the invoice.