Japanese online shopping giant Rakuten has added another company to its cart with the acquisition of Ebates, a cash-back shopping website. The $1 billion cash deal will give Rakuten 100 percent of Ebates voting stock. Founded in 1999, Ebates is a membership-based shopping portal headquartered in San Francisco that offers rebates and coupons from other large retailers such as Amazon.com and Walmart. Members can get deals on everything from patio furniture to hotel accommodation.