Need help, think this might be a bug, ZC 1.3.02, tax not calculated

http://www.zen-cart.com/forum/showthread.php?t=40630

I have posted this on the bugs forum (link above), but so far have not seen replies.

I'm not sure if this is a bug or just me, could someone please confirm this?

I've have put my store down for maintanance for the time being. My profit margin is small for many items and if I don't collect sales tax on some orders I'm breaking even or lose some money because I'm the one responsible for paying the sales tax. I don't want to contact customers and tell them they owe sales tax the cart didn't charge, this seems unprofessional and might cost future sales, I'll just take the loss instead.

If anyones has any suggestions to fix this problem please let me know.

Thanks.