An audit performed by federal investigators finds that the U.S. Census Bureau wasted millions of dollars in preparation for the 2010 census.  Thousands of temporary employees either picked up $300 checks without working one day or overbilled for travel costs. For example, 23 temporary census employees were paid for car mileage costs at 55 cents a mile, even though the number of miles they reported driving per hour exceeded the total number of hours they actually worked.