"From the New York Times:

In its Sept. 13 decision, a three-judge panel of the United States Court of Appeals for the District of Columbia Circuit held that the rate increase failed to meet the Administrative Procedure Act’s “requirement for reasoned decision making.” In fact, the reason the Postal Service gave when challenged in court by a frequent adversary, a California lawyer named Douglas Carlson, was close to bizarre. It needed to keep the price of stamps “at round numbers divisible by five,” it asserted, for the sake of the “simplicity of structure” required by the Postal Accountability and Enhancement Act.

This did not go over well with the judicial panel. “By its plain terms, the statute refers to the simplicity of the pricing schedule as a whole,” Judge Neomi Rao wrote in the unanimous opinion. “It is not a provision about simple consumer prices, as suggested by the Postal Service.” Judge Rao quoted with approval Mr. Carlson’s arguments that consumers “may not appreciate the supposed ‘convenience’ of a higher price” and that “the public had never struggled to understand the price of stamps, even though that price had not been divisible by five for most of the nation’s history.”"

"Maybe it had been a ploy to start to a tradition of 5 cent increases."