The issue I have reported on October 16, 2019 is a BUG.
Steps to reproduce:
1. Install VM 3.6.8.10197 from VirtueMart3.6.8_Joomla_3.9.13-Stable-Full_Package.zip (
http://dev.virtuemart.net/projects/virtuemart/files)
2. Install sample VM entries
3. To make things easy to reproduce define this both VAT entries per product:
- 7% Vat tax per product
- 19 % Vat tax per product
4. In products list assign to 'Root Pattern' final price: 10 (per 'Calculate the Cost price') and 7% VAT
5. Open the payment method 'Cash on delivery' and empty at 'Configuration' the field 'Fee per transaction', also set 'Tax' to 'Apply no rule'
6. Create a new shipment method 'standard', set a 'Shipment Cost' of 5.17 and assign 'Tax' of 19% VAT
7. Then purchase 1 item of 'Cowboy Hat', thereby select shipment method 'standard' at cart and finish checkout - see Screenshot_2019-11-09 Shopping cart
8. Open the frontend Order Information (via displayed link after checkout): any price and tax amount is displayed correctly - see Screenshot_2019-11-09 Order Information
9. Go to VM backend, open the related order in Orders List, scroll down to button 'Edit ordered products' - see Screenshot_2019-11-09 Edit Order 1
-> Only one VAT column is displayed, the column header is '7% VAT', which is wrong
10. Click button 'Edit ordered products' but do not change anything, then click 'Save'
11. The shipment VAT will be recalculated with 7%, which is wrong - see Screenshot_2019-11-09 Edit Order 2
Summary:
1. If the VAT of a purchased product differs from the shipment VAT for this product the latter will not saved correctly.
2. When editing/saving the order in the backend the (not correct saved) shipment VAT will be downcalculated to the product's VAT.
This bug I would consider as important, since the given example - different VAT amounts for product and shipment - is a common scenario. Also it is common to decrease or increase the amount of a purchased item after checkout for instance to satisfy a customers demand via email or phone call.