The annual sales tax holiday that occurs across 16 states — including Iowa — for back-to-school shoppers is set for this Friday and Saturday, Aug. 2 and 3.The “holiday” exempts customers from paying sales tax on certain articles of clothing or footwear priced at less than $100. The exemption applies regardless of how many qualifying items are bought at a time and extends to mail order, catalog and online sales ordered and paid for on the holidays, even if the delivery comes later.A full list of exempt and taxable items can be found at https://bit.ly/1IpBLlR.