Membership Taxes by Tech Republic?!!!

I renewed my membership to Tech Pro, received a receipt & then found the credit card had a different amount charged – the difference was sales tax according to customer service.
1) Since when do you send a receipt without including all charges?
2) Since when is a membership a taxable item?

I belong to several organizations & none has ever charged me sales tax on a membership before. There may well be a tax on the membership – they seem to be taxing everything now – but I had to submit the receipt for reimbursement & changing the amount now is too much of a hassle. $6 isn’t a show stopper, but it is an irritant. Customer Service wasn’t the least bit apologetic about it, either. NOT the way to go, Tech Republic.