Serious problem with taxes and coupons

-- HikaShop version -- : 3.2.0
-- Joomla version -- : 3.7.5
-- PHP version -- : 7.0.23
-- Error-message(debug-mod must be tuned on) -- : See attached information

We noticed this problem when combining taxable and non-taxable items into the same order, and then using a coupon that is not product-specific.

With both flat rate AND percentage coupons, the amount of taxes and the total amount of the order shown are wrong.

I have prepared a detailed spreadsheet with links to all the necessary screenshots. You will see that the order total and amounts are fine without a coupon. But when you test with both a % off and flat rate coupon, the calculations in the checkout are very, very wrong.

The areas in blue are reference information for how the sample site was setup. The two test scenarios are in the white boxes below.

I can provide you access to the dev site if you need it, but I think this information is self-explanatory. It's easy to reproduce using this setup.

This site was tested against the very latest HikaShop v3.2.0, downloaded today on Sept 13th, just a few hours ago.
So the software should include all current patches but alas, it's still very much broken for coupons and taxes.

Did you even look at the file? Everything is there, laid out, with links to every screenshot. Including the coupons.

Also - if you don't like to work with Excel files, why does your forum accept them as an allowed file format?

Please review what I have sent. I have put considerable effort into giving you a very clear set of information and screenshot about what is happening. I'd appreciate you making a similar effort to review it.