From mid February 2014 we started using a new order management system that produces invoices in a slightly different way to our Shopping Cart.
The most notable difference has come when orders are based in a currency other than Pounds (GBP), did not include VAT or have been discounted in some way.
The result is often a line on the printed invoice indicating a “Totals Adjustment“.
The reason for this line is that the cart will calculate an order based on the individual product line cost including any floating numbers past the usual 2 decimal points (eg: 1.325051 instead of the visible 1.3). Line totals (quantity x product line cost) are displayed as rounded but the final order total will reflect the non-rounded value, totalled up.
It’s for this reason that the cart order totals viewed in a non-GBP currency, can sometimes fail to add up as shown.
Our order management system however rounds product costs and then uses that figure to calculate everything based on that. It does not carry a hidden few decimal points to confuse things.
Bottom line, the issue is caused by number rounding issues and ultimately the price paid on the cart is the correct one.