Totals for invoices can all be set to exclusive except discount

[apiuser]

Feature request from maderlock, posted on GitHub Jul 21, 2016

Steps to reproduce

1. Install 2.1.0
2. Set discount to be applied to inclusive total and customer tax to be calculated after discount
3. Set invoice, order display settings to display all as exclusive of VAT
4. Place an order with a discount
5. View invoice

Expected result

1. Subtotal + shipping - discount = grand total (excl tax)

Actual result

1. Subtotal + shipping - discount = slightly less than excl grand total as discount includes amount applied to inclusive subtotal

I would suggest there is a similar option to display discount incl/excl of VAT. The latter would add back the discount_tax_compensation amount so that the totals add up.

See example for why this currently is rather unintuitive:

[apiuser]

Comment from maderlock, posted on GitHub Jul 21, 2016

I should note that the same issue exists in pdf. Looking at the discount values in module-sales/Block/Adminhtml/Totals.php, the correct value would be $this->getSource()->getDiscountAmount() + $this->getSource()->getDiscountTaxCompensationAmount() and similar for base. However, if I do this I end up with a 1p error in the order, though not the invoice! I thought the rounding since 1.8.1 sorted this?

e.g.

v.s.

[Fooman]

I'd classify this as a bug.

[c3media_robert]

Yes, I thought this was a bug, which is why I raised it on github. It was then moved here as it was classified as not a      bug(!)