Wow. Just spent 15 frustrating minutes with XC5 demo admin.
1. Sales Tax module is disabled and no way to enable in demo mode;
2. I read the docs:
http://kb.x-cart.com/display/XDD/Specifying+sales+tax+for+your+products
3. There appears to be no way to import or export sales tax rates/zones;
4. The demo store admin is slow as molasses;
...and it is very clear that sales tax is not ready for production.
XC4 tax interface may be perceived as too complicated, but it has the features.
based on the docs, XC5 tax features are simply missing.
And not having tax system enabled on the demo admin makes it impossible to test without installing.
Dear X-Cart: in the US, there are states that have 90+ tax zones (New York is one) and some states require collecting tax on shipping, some states do not. XC5 is useless for production until it can import tax zones from a spreadsheet and there is a setting per tax zone to apply to DST+SH or just DST. Or ST. With or without shipping.