I've always thought of subtotal as a calculated value that is not the final amount on an invoice (for example, a sum of individual prices before discounts/taxes are applied, or the total for a selection of items depending on how the invoice is itemised). The absolute final amount (after all calculations) is then the total.
But, I'm working with a third party shopping cart and it seems to insist on calling the final total subtotal. Is this acceptable, or should I fix this?
I think people are fixing on the specific situation I bring up in my question rather than the general 'subtotal' vs 'total' - I'm pretty sure I've seen other receipts/invoices where 'subtotal' is used where I'd have thought 'total' would be more appropriate.
I'm asking which would be the correct word for the final amount on an invoice after all calculations and considerations.