Amazon is quickly becoming a capitalist giant. The company just rolled out another benefit for its Prime members, called the Amazon Prime Rewards Visa Signature card. Amazon already has three credit cards, so how is this one different? Two of the cards can only be used with Amazon and the Rewards Visa can be used at any retailer, but provides three percent cash back on Amazon purchases. The newest card is an upgrade on the Visa, offering 5 percent cash back on Amazon purchases.