Whole Foods customers are reaping the benefits of Amazon's $14 billion acquisition of the organic-food store chain in 2017. After slashing prices and offering extra discounts to Prime members last year, Amazon is now giving Whole Foods shoppers 5 percent back when they use their Amazon Prime Rewards Visa card.

Jeff Bezos' company has just announced the perk, which it no doubt hopes will encourage more people to join the $99 per year program and sign up for one of its visa cards, which also offer 5 percent back on Amazon.com purchases.

Even Amazon customers who aren't Prime members can benefit; when paying with an Amazon Rewards Visa Signature card in Whole Foods outlets, they'll earn 3 percent back---the same deal that is available with Amazon.com buys. Additionally, both Prime and non-Prime cardholders earn 2 percent back on gas stations, restaurants and drug stores, and 1 percent back on all other purchases.

The cards come with other advantages, including no foreign transaction fees, travel protection, no rewards cap or expiration date on the rewards, and zero fraud liability

"We've seen incredible excitement and adoption around our Amazon Rewards Visa Credit Cards and are thrilled to partner with Amazon and Whole Foods Market to bring even more rewards to our joint cardmembers," said Leslie Gillin, president of Chase Co-Brand Cards, in a statement.

It seems one group who aren't pleased about Amazon's takeover is the Whole Food employees themselves. Workers say a new inventory management system called order-to-shelf, or OTS, has led to food shortages within the outlets. Some employees reportedly called OTS a "militaristic," moral-crushing system that has led to goods being out of stock and empty shelves.