Show the "Update" button on checkout on the new orderforms (to update totals)
When under WHMCS Settings -> Ordering, one of the "old" orderforms (boxes, modern etc) is checked, then there's a "Update" button when tax/VAT options are enabled in WHMCS, so that the customer can see the actual amount he's going to pay, after changing his State/Country or adding his VAT ID (to become exempt).
The new orderforms (standard_cart, premium_comparison etc) don't have this and the "Total Due today" amount in the green box won't auto update when the customer enters his VAT ID (to become VAT exempt) or changes his country (were a different tax percentage would be applied). As a concequence, if the customer changed his country to one with a higher VAT rate than the default, his invoice will have a different amount than what is shown in "Total Due today" - which can cause misunderstandings (especially if the customer paid via credit card during checkout and realizes he's been charged more).
So it would be great if the "Update" button is added to the new orderforms as well, so that when someone enters his VAT ID or changes his country, he can click the Update button, and get see the updated amount in "Total Due today".