I've never heard of this. I believe that Massachusetts is one of the states (so far) that don't require that you pay sales tax for online purchases. Which means you'd be paying a tax unnecessarily if this were for online purchases. Also, clothing is not taxable in Massachusetts, how can you charge a sales tax on something which is not taxable? In fact, how can you charge a sales tax when you haven't yet purchased a tangible item? I think there's something wrong with the store/web site which is doing this.