Starting Sunday, it's going to cost an extra penny to send a first-class letter via the cash-strapped U.S. Postal Service.

The increase means it will cost you 45 cents to send a letter within the United States.

So if every penny counts and you're running low on stamps, it may be worth your while to buy a sheet or two of Forever stamps today or Saturday. You'll pay the lower price but the stamps will be good "forever."

In addition to the one-cent increase on a first-class letters, other rate increases that begin Sunday include:

• a 3-cent increase in postcards to 32 cents.
• a 5-cent increase to 85 cents for 1 oz. letters sent to Canada or Mexico.
• a 7-cent increase to $1.05 for letters send to other international destinations.