For the retail industry, customer emails are currency.

Get that address, and a company can personalize customers' future experiences, targeting them for discounts and promotions that could make them more likely to become repeat customers.

The responsibility to capture those emails often falls to the sales associates working the floor. In fact, collecting emails and signing customers up for loyalty programs is a big part of those jobs now, said Jill Dvorak, senior director of digital retail for the National Retail Foundation.

But workers at Five Below, the Philly-based national discount chain that's made headlines for thriving in the age of Amazon, say there are consequences when they don't. They're told email collection affects how many hours they get each week.

Tiffany Rogers, a recent Parkway Center City Middle College graduate who worked at the Five Below on Columbus Boulevard for five months, said she was told she had to get emails from 25 percent of the customers she rang up.

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In February, after watching her hours dwindle from more than 20 a week during the holiday season to 10 to 14 after New Year's, she got scheduled for just four hours two weeks in a row. When she asked her manager about it, he told her it was because she wasn't getting enough emails.

"You have to get the emails," Rogers said her manager told her.

It wasn't easy. These were people who were buying a slime kit or a bag of sour gummy worms for a few bucks and they'd usually get defensive. What do you need my email for? they'd ask. She didn't actually know. It was never explained to her.

Sometimes, out of desperation, her coworkers would make up emails just to satisfy their bosses, but she was afraid she'd get in trouble if she was discovered.

Five Below workers across the country who posted on job review sites such as Glassdoor and Indeed had similar accounts, some saying their ability to get a raise was also tied to their ability to get emails.

"You have to get at least 20 percent in e-mails every week and sometimes [it] can be difficult because a lot of customers want to get in and get out or consider Five Below e-mails spam," wrote one former employee in Columbus, Ohio, who otherwise rated the job with five stars last December. "Sometimes one of our shifts would get taken if we didn't hit 20 percent."

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A former manager in Hopkinsville, Ky., wrote in April: "You have to obtain e-mails from customers and if you don't they hound you to the point of quitting."

Five Below marketing manager Dana Zuppo said there is no email quota for cashiers, nor are there incentives for workers to collect emails.

"The email ask at the register," she said, "is simply to benefit the customer, allowing them to stay in tune with the brand."

In a recent earnings call, the same day Five Below's stock rose to nearly $100 a share, the highest it has been since it went public in 2012, CEO Joel Anderson said a new point-of-sale system would begin to hit its more than 650 stores later this year. It's one that "provides the functionality and flexibility" for such features as a loyalty program. (Some in the industry recommend using email receipts or digital payments in order to more easily sign customers up for promotions at the point-of-sale.)

Dvorak of the National Retail Foundation said she hadn't heard of retailers using email quotas, but, "if they are out there, hopefully they're emphasizing quality and interest."

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She pointed out that email collection is about quality over quantity — they're only valuable if they result in customers making follow-up purchases.

She advises giving customers incentives: Offer a newsletter that will include exclusive promotions for a specific zip code or a discount for signing up. And, she said, it's also important to train your workers to know when and how to ask, so it's done in a respectful way that will make customers more likely to give their emails.

When it comes down to it, retail workers often complain about unrealistic job demands because they fear they'll be fired, said Chelsea Connor of the New York-based Retail, Wholesale, and Department Store International Union. This lack of worker protections is one reason organizations such as OnePA are advocating for a "fair workweek" law that will regulate how retail companies schedule their employees.

"You're effectively measuring someone's success on someone's willingness to give over their personal data," Connor said. "That doesn't make sense."