However, i’ve identified the problem … and have a workaround but no solution …
First of all the identified situation:
The installation is within a German environment (uses “.” as 1000s seperator and “,” as Decimal Symbol)
The vat values are defined as an drop down list array where are the keys the VAT values used for the calculation.
These keys are defined with “.” as Decimal Symbol (and can’t be defined with “,” because this is not allowed by the Dropdown Editor)
The (JavaScript) format coversation for 20.0 results in 200 and is the source for the bad calculation…
Workaround: Change the vat_list keys to use “,” directly in the source file.
ex.: custom/application/Ext/Language/en_us.lang.ext.php
from
$app_list_strings['vat_list']['17.5'] = '17.5%';
to
$app_list_strings['vat_list']['17,5'] = '17.5%';
But beside this problem, may it is also a structural problem.
To have the VAT list defined in language settings file is a bad situation.
The UI language does not define the possible VAT values
VAT values depend on countries, more specific. depend on the billing country …