The shopping list for the new school year is long, and it encompasses small items such as erasers and glue and big-ticket purchases like computers. And the kids need clothes and shoes, too! Parents will spend an average of $673.57 on back-to-school shopping in 2016, according to the National Retail Federation. Smart shoppers can take some of the sting out of back-to-school season by taking advantage of cash-back credit cards — and, in some states, sales-tax holidays.