Craftsman does sell a tool that will remove rounded nuts,sorry I cant remember what its called but Sears should know,Maybe if you can get them to lock down on the nut,use a good pair of vise grips...I know they saved me more than I can count.Good Luck.Also if you can get to the head of the bolt maybe an ease out would work,drill into the head,then put the ease out in and use a wrench to back out the bolt with the vise grips holding the nut from moving,could work maybe.