NEW YORK (CNN/Money) - Cash may be king, but the burger behemoth McDonald's Corp. is giving a little more credit to plastic at its restaurants.

The world's largest fast-food company has told analysts that it's boosting plans to provide credit, PIN-debit and signature-debit card payment options at more restaurants by the end of the year.

Chief Financial Officer Matt Paull told analysts during the company's earnings conference call that its cashless payment options are now available at more locations, about 4,500 of its 13,600 restaurants in the United States.

In late March, Oak Brook, Ill.-based McDonald's (MCD: Research, Estimates) announced it had partnered with American Express to introduce plastic payment at about 3,000 restaurants, and expected to double that target by the year-end.

"It's a convenience issue and it also speeds up service," Paull said. Additionally, McDonald's said its average check of cashless transactions was higher than for cash payments, helping to lift overall average check transactions.

The burger chain reported second-quarter earnings Thursday that jumped 25 percent, its best sales growth for that quarter since 1987, as McDonald's began to expand successful U.S. menu items like salads into Europe.

The company has seen U.S. sales rebound in the past year, bolstered by menu and operational improvements at existing restaurants in lieu of expansion.

Paying with plastic isn't the only thing its customers have to look forward to. Micky D's unveiled plans earlier this month for a one-of-a-kind futuristic flagship store in Chicago to commemorate the company's 50th anniversary next year.

McDonald's founder Ray Kroc opened his first restaurant in Des Plaines, Ill., on April 15, 1955.

The birthday Happy Meal boxes with the special edition teenie beanie babies are available until Aug. 19.

The new restaurant will have wireless Internet access, a roof with greenery integrated into the design, and interactive technology that the company said is currently under development.

And to mark the 25th anniversary of its Happy Meal, McDonald's is including a limited edition of collectible Ty Teenie Beanie Babies in the birthday meal boxes available through Aug. 19.

The 12 new Beanie Babies are dressed as McDonald's icons and McDonaldland characters such as Ronald McDonald the bear and Hamburglar the bear and Happy Meal the bear.

"Many parents today can remember going to McDonald's as a child and the thrill of opening the Happy Meal box to see what toy was inside, and they share that excitement today with their own children," Kathy Pyle, director of family and kids marketing for McDonald's said in a statement.

"We're excited to bring back one of the most popular Happy Meal offering to celebrate the 25th anniversary of Happy Meals."