The cost of a first-class stamp will increase by a penny, to 45 cents, as of January 22, 2012. Rates to Canada and Mexico are increasing a nickel to 85 cents and other international destinations will be $1.05, an increase of seven cents, according to the U.S. Postal Service. In addition, the cost of mailing a postcard will go up three cents to 32 cents. That's the second postcard rate increase in less than a year.
