Here's what Costco workers are actually looking for when they check your receipt at the exit

One of America's favorite retailers, since it first opened its doors in 1983, has become a place to get your favorite items in bulk, so you can save money.

One curious thing about the checkout process at the stores is likely to be noticed by die-hard fans and regular shoppers. After cashiers have rung up their orders, bagging their purchases, and customers are almost out the door, there's still one more receipt check.

This last receipt check is all about something. Insider reached out to a number of employees, who spoke on the condition of anonymity, to get the scoop on the last receipt read-through.

There are 13 things you can get at the store for $10 or less.

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"It is to make sure you have what you paid for, but it is also to make sure you don't have what you didn't pay for," said an employee of the warehouse club.

More specifically, however, another elaborated that the employees at the store are looking for things when customers leave.

1. A code on the top and bottom of the receipt that changes daily so employees know the receipt was, indeed, printed that day.
2. The item count on the bottom of the receipt to make sure there were no under or over charges.
3. High-end items such as jewelry; stamps; electronics; or items over $300, which need supervisors' initials on them. 
4. Large items like tissue and water, which have various signifiers on the receipt to ensure final checks include a look at the bottom of the basket.

On its own website, Costco has made clear its policy.

The company wrote on its website that "it is standard practice at all our warehouse locations to verify purchase receipts when customers leave our buildings." This is done to make sure that the items purchased have been processed correctly. It's our most effective method of maintaining accuracy in inventory control, and it's also a good way to make sure that our members have been charged correctly for their purchases.

It's not the only big box warehouse chain that checks shoppers' receipts. Sam's Club and BJ's do the same thing.

A Sam's Club representative said in a statement that all receipts and merchandise will be inspected as you leave the warehouse to make sure that all members are charged the correct amount.

The employee recounted an attempted theft while doing the check. A produce box full of clothes was tried on by someone exiting the store.

I asked him if he had a receipt for the clothes after he passed me. He said that his wife was waiting in the car. He gave me a hard time until he saw my manager walk towards me and threw the box on the ground.

The last check of shoppers' receipts is important for both customers and employees.