Whilst editing orders in the back office, you can choose to add a monetary discount to an item or order total or percentage discount an order total. Below you will see the page layout and it's content.

Values for each product including delivery charges, VAT and order total. When adjusting these prices, such as total order value, you will have to amend the other values such as VAT. If you also enter a percentage or monetary value, you will still have to adjust the prices as it is a manual adjustment. Once you have made any amendments, simply click 'Update Order Prices' and you will return to the order edit page. You may also choose to leave a note on the order for future reference and this is done on the order edit page.