GX-Entwicklung

Steps to reproduce:

1. Gambio Admin > Modules > Module-Center: Install the "Gift vouchers and coupons" module
2. Gambio Admin > Modules > Order Total: Install and activate the ot_total_netto module
3. Gambio Admin > Modules > Order Total: Install and activate the ot_gv module
4. Place an order (don't use Klarna as payment)
5. Gambio Admin > Orders: open the order
6. Edit the order by clicking on "Edit" in the products box
7. Open the "Shipping Methods, Payment Systems and Sums" tab
8. Add a Gift Voucher: "Voucher:" with a value of "1" and click on Save in the same line
9. Check the checkbox "Finish and recalculate" in the bottom right corner and click on Close

Expected result:
"Total, No Tax" value was reduced by 1 EUR

Actual result:
"Total, No Tax" value was increased by 1 EUR