Almost two-thirds of Americans feel the current economy isn't working for them. Customers with Costco credit cards just got a new benefit that can help ease financial strain. Costco offers cardholders a generous cash-back perk on a popular product. In the roughly 20 years that I've been a Costco member, not once have I found myself questioning whether to keep paying for warehouse club access. Granted, these days, I have a household of kids to feed, so it makes sense to keep my Costco membership f ...