FRAMINGHAM, Mass. — First it was OfficeMax, now Staples reported sales and earnings that were reflective of a struggling retail sector. The company reported that total sales for the first quarter of 2012 were $6.1 billion, a decrease of 1% in U.S. dollars and flat on a local currency basis compared with the first quarter of 2011. Net income for the first quarter of 2012 decreased 6% year-over-year to $187 million. Diluted earnings per share, on a GAAP basis, decreased 4% t to 27 cents from 28 cents achieved in the first quarter of 2011.