Kevin Brasler recalls barraging an obliging salesperson with questions about car seat safety when he was a concerned new parent.

Before they checked out, Brasler and his wife found the seat they were considering for $50 less on Amazon. But they were so invested in their in-store experience that they bought from the salesperson anyway.

However, they likely could’ve purchased the car seat in store and gotten the Amazon price by simply asking the retailer to match it.

Price matching typically requires asking the cashier to meet a lower advertised price at the time of purchase or asking a representative at the customer service desk for a price adjustment within a post-purchase grace period. To price match online, call customer service. You’ll usually need a digital or physical ad for evidence of the lower offer, and there can be exceptions and exclusions.

Brasler is executive editor at the nonprofit Consumers’ Checkbook. The group has found that mystery shoppers saved considerable amounts by price matching, including $140 on an LG sound bar speaker system at Best Buy.

Even though price matching works, less than 10% of consumers do it, according to Sucharita Mulpuru, chief retail strategist for annual commerce industry convention Shoptalk. She says that although price matching has grown during the last decade, many consumers are still unaware of it, and others don’t bother because it seems like a hassle. And some stores keep such a close eye on pricing that matching isn’t often necessary.

“As these price-matching policies have become more generous, the pricing algorithms for these companies have also become more sophisticated, so you generally don’t find yourself as a customer in a situation as much where you can go to a retailer and say, ‘gotcha’,” she says.

And stores that advertise price matching aren’t a surefire bet for the best deal. But it’s still worth doing, according to Nanda Kumar, professor of marketing at the University of Texas at Dallas. After all, you won’t save any money by shopping at a store with such a policy if you don’t actually use it.

“You need at least some segment of customers to regulate the pricing behavior of retailers,” Kumar says.

Here’s how you can price match:

Courtney Jespersen is a staff writer at NerdWallet, a personal finance website. Email: Twitter: @CourtneyNerd.

This article was written by NerdWallet and was originally published by The Associated Press.

The article Use Price Matching to Avoid Leaving Money on the Table originally appeared on NerdWallet.