The Amazon Prime Rewards Visa Signature Card already earns 5% cash back at Amazon and Whole Foods, and for a limited time, another retailer is joining that group. Through Sept. 21, 2021, the card will also earn 5% cash back at Zappos, a major online shoe and clothing merchant. (Amazon owns both Whole Foods and Zappos.) Cardholders are... Kimberly Palmer is a writer at NerdWallet.