The U.S. Postal Service is seeking the highest price hike on stamps in three decades. The struggling agency proposed a 10 percent increase in the cost of a first class stamp, bringing each little square to 55 cents. It’s also seeking a more than 12 percent increase in rates for other shippers like Amazon. The Postal Service said the overall increase in prices is only 2.5 percent, though, because it’s cutting prices elsewhere.