The back-to-school sales tax holiday is underway in Texas. The annual retail event started just after midnight this morning. Most clothing, school supplies, footwear, and backpacks that sell for under $100 qualify for the exemption. The waiver applies to purchases made in person or online. Shipping costs for online purchases are considered part of the total price. Items such as jewelry, purses, and luggage don't qualify. The sales tax holiday continues until midnight Sunday night.