Parents around the country this year will collectively spend billions on back-to-school supplies—though not quite as much as last year—and they’re holding off on making purchases until they deem the time to be right, a new analysis shows.

The average family with children in grades K-12 plans to spend $630 this year on digital tools, clothing, classroom supplies, and other goods, according to recently released figures released by the National Retail Federation. That’s a drop from $669 in 2014.

The National Retail Federation projects that total pre-college back-to-school spending will reach $24.9 billion this year. Since 2005, families’ average spending has jumped 42 percent, from $444 to $630.

Of the current amount that the average family is spending, $217 will be devoted to apparel, and about $197 on electronics, said Pam Goodfellow, principal analyst at Prosper Insights & Analytics, which conducted the federation’s research.

The National Retail Federation describes itself as the world’s largest retail trade association, one that represents a wide variety of stores, merchants, restaurants, retailers, and others.

The dip in spending on back-to-school supplies is in one sense not unusual, Goodfellow said. Spending tends to bounce up and down from year to year, as families buy more freely in some years, then hold back the next, in a “replenishment year” in which they rebuild their savings, she said.

The federation’s research also indicates that while overall consumer confidence is increasing, families in 2015 kept their impulses to spend on back-to-school goods largely in check, Goodfellow said.

More families are also holding back on their spending until school is about to start. Thirty percent will do their back-to-school shopping in the final run-up to the beginning of classes—one to two weeks before the doors open—up from 25 percent the previous year, the data show.

Families’ unhurried approach to buying is probably based on a conviction that they will find better deals if they wait, and that they “have an upper hand with retailers,” Goodfellow said.

Buying—With Hygiene in Mind?

A separate estimate of back-to-school spending, meanwhile, suggests that parents aren’t just focused on things that will help their kids academically—but also things that that will keep their sons and daughters clean.

TeacherLists is a Massachusetts-based company that operates a proprietary platform for educators to share school supply lists with families. The idea is to allow easily and efficiency share that information with parents, who can access them in a variety of forms—via smartphones, home computers, or in stores, or on retailers’ websites. “No more searching through backpacks or emailing teachers,” the company says.

This year, not all of the back-to-school spending was of the pen, paper, and notebook variety, TeacherLists found. 

An analysis of 300,000 of those lists shows an increase in families buying cleaning supplies, such as tissues, hand sanitizer, disinfectant wipes, TeacherLists reports.

Overall, the average back-to-school supply list for elementary schools had a $70.93 pricetag, TeacherLists reports. It was $91.14 at the middle school level, and $157.58 at the high school level. (The retail federation’s numbers are much higher because they include a lot of other categories of spending, beyond simply what educators are asking families to buy, explained Tim Sullivan, the founder of the company, in an interview.)

Sullivan attributes the spending on those items on cleaning products partly to schools lacking the money to cover those costs on their own. Parents are taking up the slack.

“Something’s going to give,” he said. “School budgets are as tight as ever.”