l10n_it_edi Error with tax price included

[BitStab]

Impacted versions:
V12

Steps to reproduce:
- Install Accounting, l10n_it, l10n_it_edi
- Create an italian company and configure
it, use italian chart of account

Create an invoice, containing a product with tax included in the sales price. change the quantity to f.e. 6.

Current behavior:
In the electronic invoice XML the single price is ok, but the subtotal of the line is wrong because of rounding errors.

In the picture you can see the calculation error. The original price including 10% tax is 1,50€
The check of SDI gives the error "PrezzoTotale calculated incorrect", because they check it with a simple mathematic proof:
Price * Quantity = PrezzoTotale
If this doesn't apply they refuse the invoice with this error

Expected behavior:
correct calculated subtotal on lines. In the given case of above it would be the following:
1,5 / 1,1 = 1,363
1,363 * 6 = 8,18 (rounded)
For this it is important to have 3 digits after the decimal point on the single price field of the XML.