WASHINGTON (AP) _ Businesses are disappointed, bruised, angry and - in some cases - relieved at the new postal rates scheduled for January. Some feared the increases would be worse.

The extra three cents for a stamp is a trifling amount to some people, but the higher rates will cost business millions. The changes will net the U.S. Postal Service an extra $4.7 billion in 1995 according to the Postal Rate Commission, which approved the new charges Wednesday.

John Sutter, publisher of The Yankee Trader, a shopper published in New York, termed the new rates hurtful to the small businesses that advertise in his mailed paper.

''The commission's decision ignores the voice of the customer,'' complained Robert Kamerschen, chairman of the Windsor, Conn.-based ADVO, the nation's largest third-class mailer. He said the higher rates punish advertising mail even though it costs the post office less to handle.

''This is going to hurt a lot. ... They don't seem to get it that pennies at the Postal Service means big dollars to our store,'' said Adrian Fredericks, owner of Five Buck Pizza in Provo, Utah.

''For the hundreds of thousands of mom-and-pop stores who rely on mailed community papers, coupon programs and other third-class advertising to keep in touch with customers, this decision really hurts,'' added Donna Hanbery, executive director of the Minneapolis-based Alliance of Independent Store Owners and Professionals.

The new rates, expected to take effect in January, increase the cost of business mail more than the post office had suggested, while reducing some proposed raises in first-class rates.

''The early returns are that those who got a higher rate, of course, are not happy about that,'' said Arthur Sackler of the Mailers Council. His Washington-based coalition of major mailing groups had spearheaded a plan for an across-the-board 10.3 percent rate increase for all types of mail.

But, Sackler said, the changes the rate commission made in the Postal Service's original plan were not severe. ''Nobody is either jumping for joy or jumping out windows,'' he said.

''It's not as bad as we feared,'' agreed business mail consultant John Jay Daly of Chevy Chase, Md., who said he had warned clients that the commission might raise their rates as much as 18 percent.

The rate commission decided on a 14 percent increase for mailing advertising and publications while holding the increase in first class to about 8.9 percent.

For some large companies the increase could cost more than $20 million next year, said Tom Shimko, vice president of Pitney Bowes Mailing Systems.

The commission ''has penalized what has been a profitable sector of postal business,'' Jonah Gitlitz, president of the Direct Marketing Association, contended. Advertisers may have to find other ways to deliver their message, he said.

''We kind of got boxed around,'' complained Brian Hummell of the Alliance of Nonprofit Mailers. He said periodicals issued by environmental, charity and similar nonprofit groups face increases of up to 25 percent.

Still, Shimko said, a study conducted for Pitney Bowes found many firms expecting to increase their mailings next year despite the higher rates - though he said many will be looking to automation and other ways to cut costs.

While the rate commission agreed to the basic 32-cent first-class price proposed by the Postal Service, it refused to raise the price of heavier items to 25 cents per added ounce. Instead, the commission wants the added weight to remain at the current cost of 23 cents per ounce.

The big winners in that decision will be business such as banks, insurance companies and brokerages, which tend to send heavy first-class mail.