Yes, the State of Texas requires that businesses charge sales tax. The sales tax rate including City of Keller taxes, is 8.25 %
If you see a painting that you want, you can click on the "Buy Now" button to calculate the associated sales tax.
If you live in a different state than Texas, and the painting will be delivered outside Texas, then you do not have to pay sales tax. There is an option on the "Buy Now" screen to let you calculate the final total cost without sales tax.