PROVIDENCE, R.I. (AP) —When Katrina Gamble goes grocery shopping, she brings her list and her bags — a pair of sturdy canvas bags she bought a few months ago for $4.99 at her local grocery store.

"It works just as well," said Gamble, 30, a political-science professor at Brown University, adding, "It's better for the environment."

A growing number of stores are catering to customers like Gamble, who see reusing shopping bags as an easy way to cut down on waste.

Several large retailers, including Stop & Shop, New England's largest food retailer, and housewares store Ikea, now sell reusable shopping bags, and some groceries, including independent stores and natural foods chain Whole Foods, go a step further, offering credits of a few cents for each bag that's reused.

There's an upside for stores, too: Giving out fewer bags means the store saves money.

The fashion world has also taken note, with designers like Stella McCartney and Hermes selling reusable shopping bags for hundreds of dollars.

Whole Foods created a frenzy in New York last month when it offered a limited number of designer shopping bags for the bargain price of $15.

The Sierra Club's Sierra magazine estimates that Americans throw away almost 100 billion plastic bags each year and only one to three percent are recycled.

Environmentalists warn paper is not much better than plastic because trees have to be cut down and energy expended to make them.

They also say cutting back a little could make a big difference. The Sierra Club estimated that if every person in New York City used one less grocery bag per year, it would reduce waste by 5 million pounds and save $250,000 on disposal.

Several companies give incentives for customers to cut down on disposable bags.

Eastside Marketplace, an independent grocer in Providence where Gamble shops, gives customers a 3¢ -per-bag credit when they reuse a bag.

Even with the credit, the store saves a few pennies or breaks even because it doesn't have to pay for a disposable shopping bag, said spokeswoman Kim Moreau. About seven to ten percent of customers reuse bags, she said.

"I wouldn't even call it a trend anymore. It's more like a growing way of life," Moreau said.

Austin, Texas-based Whole Foods gives 5¢ to 10¢ back for each reused bag.

Even more traditional supermarkets like Stop & Shop are introducing reusable bags.

The Quincy, Massachusetts-based company doesn't give a bag credit. But it started selling sturdy reusable green bags with a Stop & Shop logo for 99¢ in November.

Since then, the company said it has sold or given away 1.3 million bags to shoppers.

"Our biggest challenge is keeping them in stock because the customers are really responding to them," spokesman Robert Keane said.

It's that green bag that prompted Allison Spooner, 37, of Providence, to give up disposable bags. She said she had been thinking about environmental issues but hadn't found a reusable bag she liked.

Then she saw Stop & Shop's bag, which is more sturdy than a regular paper grocery bag, holds more groceries and is made of recycled material. It hasn't been hard to adjust, she said.

"I take all my groceries out when I get home and put the bags next to my purse so I don't forget them," she said.

Swedish retailer Ikea has perhaps taken the reusable bag idea further than any other large chain. In March, Ikea, which sells everything from furniture to dishes to Swedish meatballs, began charging a nickel for a plastic shopping bag.

A reusable bag costs 59¢. The goal was to reduce plastic bag usage by 50 percent, and the company has already exceeded that, said spokeswoman Mona Astra Liss.

A similar policy at Ikea stores in Britain reduced plastic bag usage by 95 percent within nine months, she said.

Then there are large wholesale stores, which don't use bags at all. BJ's Wholesale Club, based in Natick, Massachusetts, Sam's Club, based in Bentonville, Arkansas, and Costco Wholesale Corp., based in Issaquah, Washington, instead reuse the boxes used to cart merchandise.

The reason has little to do with the environment, said Dick DiCerchio, Costco's chief operating officer of global operations.

"The cost of bags are a big cost of doing business in a typical grocery store," he said.

But even Costco is looking to cut back on boxes. It's been testing out sales of reusable bags in Canadian stores, where they've been a big hit, and this month started selling reusable bags in the San Francisco Bay area, a two-pack for $1.79.

Joe Portera, chief operating officer of CostCo's eastern and Canadian divisions, said if the bags are a success, Costco could then ask suppliers to stop packing products in boxes and put them on pallets instead.

"It would save money not only for us but for manufacturers," he said. "It would ultimately reduce the amount of waste and recycling that's necessary with cardboard."