The price for mailing letters is officially going up starting Sunday.The price for a First-Class Mail Forever stamp is increasing by five-cents from 68-cents to 73-cents, according to the United States Postal System (USPS) website.Forever stamps, first issued in 2007 when they cost 41-cents, remain valid for full First Class Mail postage no matter when the price increases after their purchase. It’s not the only item seeing a hike in price.Mailing one ounce metered letters in-country is increasing by five-cents from 64-cents to 69-cents. The additional-ounce price for single-piece letters increases from 24 cents to 28 cents.The price for mailing ...