Old website with C5's E-Commerce failing to calculate tax on some purchases

I created the following years ago for a client, ttps://www.rockermanoftexas.com, and it has been humming along with no issues until recently. It fails, sporadically, to calculate and add sales tax and it's screwing up his accounting. I have already created a new version of this website using Community Store for the very reason that this is so old and unsupported but he is now working on a new design for the website we were about to launch and it is on hold and, in the meantime, he is wanting me to see what someone would charge to diagnose and fix the sales tax issue. Please let me know.

View Replies:
smith12 replied on at Permalink Reply
Hi James, I can help you. Please check PM
JohntheFish replied on at Permalink Reply
Old eCommerce issues could be related to incomplete update for php version compatibility. Here is my list of updates. http://www.legacy.c5magic.co.uk/add-ons/zone-based-shipping/php7/...
ConcreteOwl replied on at Permalink Reply
Since this is a installation, it won't be running on PHP7, more likely to be PHP5.6.
There are issues with mixed content, calling multiple http links over https and these are being blocked by the browser.
There is also an issue with 'Secure' 'SameSite' cookie settings that need to be addressed and finally there could be some serious database bloat that needs some house cleaning..