Included tax is calculated WRONG

[wunschradio]

Steps to reproduce the issue

Setting is 16 percent and tax is included. Product costs 10 €.

Expected result

Tax should be 1.38 €.

Actual result

Tax is 1.60 €

Additional comments

If the tax is excluded the rate would be right. The product would then cost 11.60 €,
But the tax is excluded so the net price of the product is 8.62 € and tax 1.38 €.
I now have to enter 13.793 to get the correct result (16*100/116).

System information (as much as possible)

Digicom Information

component
com_digicom : Core Component (1.3.11)

module
DigiCom Shopping Cart : Front end (1.3.11)

DigiCom Categories : Front end (1.3.11)

mod_digicom_menu : Admin (1.3.11)

plugin
Content - DigiCom Content Plugin : (content)

Paypal - DigiCom Pay Plugin : (digicom_pay)

Offline Payment - DigiCom Pay Plugin : (digicom_pay)

editors-xtd - DigiCom editors-xtd Plugin : (editors-xtd)

plg_finder_digicom : (finder)

System - DigiCom system plugin : (system)

System Information

PHP Built On

Database Version
5.5.5-10.0.38-MariaDB-0+deb8u1

Database Collation
utf8_general_ci

PHP Version
7.4.8

Web Server
Apache

WebServer to PHP Interface
fpm-fcgi

Joomla! Version
Joomla! 3.9.22 Stable [ Amani ] 6-October-2020 15:00 GMT

Joomla! Platform Version
Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT

User Agent
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:82.0) Gecko/20100101 Firefox/82.0