As federal income tax rebate checks hit mailboxes this week, Kmart has switched the blue light on a special Tax Rebate Cash Card. Consumers who cash their rebate checks at Kmart may convert their rebate check into a cash card with a five percent bonus. The new cards are available at Kmart's more than 2,100 locations effective immediately. The Kmart Tax Rebate Cash Card with the five percent bonus will be available only at the Service Desk. Customers may also redeem their checks at face value for cash at any register. More than $38 billion in federal income tax rebate checks will be mailed out to about 91 million U.S. taxpayers over the next 10 weeks. Households that paid federal income tax in 2000 will receive one-time checks for $300 to $600.