San Antonio-area shopping centers are expected to be busy this weekend as shoppers take advantage of Texas' sales tax holiday on many back-to-school items. The holiday from sales taxes started Friday and ends at midnight on Sunday. The easiest way to understand the Texas Comptroller's sales tax holiday rules may be to start with what's not exempt. Items with sales taxes still applied this weekend include:Clothing items or shoes valued at $100 dollars or more. Shoppers who are mistakenly charged sales taxes by a retailer may request a refund directly from the seller.