Washington (CNN) -- For small business owners like Keith Lipert, who runs a gallery in Washington, every dollar counts. He has expenses which are ever-increasing: rent, utilities, health insurance for his employees.
On top of those, each time a customer uses a MasterCard or Visa, Lipert pays a percentage -- usually around 2 percent -- in order for those payments to be processed.
It's called a swipe fee or interchange fee, and businesses are forced to add it to the purchase price. "This all adds up. ... This is a lot of money that we are having to pay," Lipert said.
These fees brought in somewhere between $38 billion and $46 billion in 2008, according to estimates from the Nilson Report, an industry publication, and the National Retail Federation. The fees eventually end up with the cards' issuers in exchange for processing the transactions.
"In the old days if you came into my shop and gave me $100, I got $100. Later you gave me a check for $100, I got $100. But today I don't. When you used a credit card, I get $98. And this is for all people," Lipert said.
The credit card and bank industries say the fees are appropriate because of the services their industries provide to businesses.
"They'll get almost instant payment and guaranteed payment for it. Whereas my card issuer, I won't pay them for another 30 days, so there's the float on the funds, which is a big component," explains Trish Wexler, with the Electronic Payments Coalition, which represents banks and credit cards.
Industry representatives also point out that merchants choose to accept the cards because they help lure customers to them, and businesses can see increased sales because of the convenience they offer by taking credit cards.
With the new credit card bill going into effect this week, some experts predict higher interchange fees as companies emphasize cards that give rewards for purchases. Those cards carry higher swipe fees.
Some merchants' groups and businesses have found allies on Capitol Hill to fight the fees. The National Association of Convenience Stores and 7-Eleven each sponsored a petition drive among customers, urging Congress to take action to give them some relief.
"The merchants are getting ripped off, it's that simple. There's monopoly power with Visa, MasterCard. They have over 70 percent of the transactions," said Rep. Peter Welch, D-Vermont, who is pushing for congressional action on the issue.
"It's a big, big expense, really much higher than it should be because of the anti-competitive, near-monopolistic control that the big banks and Visa, MasterCard have."
Antitrust regulations prevent business owner groups from negotiating with the card issuers to force a reduction in rates, and the groups are pushing Congress to give them that ability.
"I do believe as a shopkeeper, it's a service or a convenience for the credit card companies and that is ... fair," Lipert said. "My objection is that I'm not allowed to negotiate."
However, some small business owners and those who lobby for them say they would be the ones who suffer.
"Card issuers would be forced to reduce the amount of credit they extend, exacerbating the existing credit crunch. Small business owners would be severely affected by these consequences," Harry Alford, president and CEO of the National Black Chamber of Commerce, wrote in a letter to House Financial Services Chairman Barney Frank last year.
The group says many of its members rely on such cards to finance their businesses and would be "severely impacted" if credit is cut.
The card industry also says there could be unintended consequences for consumers.
"If interchange rates are forced down below what is sustainable for a card program, then rates are going to have to go up or rewards are going to have to go away," Wexler said.
Other proposals in Congress include setting or limiting fees; requiring more disclosure; and allowing merchants to steer customers away from higher-cost cards.
A big question is whether any restrictions on these fees would mean lower prices for consumers.
"If interchange fees for merchants were lowered, consumers could benefit from lower prices for goods and services, but proving such an effect is difficult, and consumers may face higher costs for using their cards," concluded a November 2009 report from the General Accountability Office, Congress' research arm.
Industry representatives point to Australia, which limited the interchange fees but did not see prices go down -- although its banking system fees are set up differently from those in the U.S.
"Large retailers are not spending millions of dollars lobbying Congress so that they can give us customers and pass it all through to us as consumers. They don't want to pay their fair share of the system and they want consumers to pay it instead, and that's not fair," said the Electronic Payments Coalition's Wexler.
Acknowledging the benefits they are getting, many merchants still believe they are paying more than their fair share.
"We need as a country to address this," Lipert said. "American consumers need to understand it's costing them a lot of money that could be put to good use in other ways."
CNN national political correspondent Jessica Yellin contributed to this story.