(USAToday) - To attract more affluent customers, the convenience store chain where many folks stop for the likes of bargain beer and two-for-one chips has begun to sell upscale wines.

Chez 7-Eleven?

Well, not exactly. But the nation's biggest convenience store chain, perhaps best-known as a place to grab a cold beer or a Slurpee, has quietly begun to sell ultra-premium wines at about $19.99 at 700 locations in 16 states.

The move is a serious bid to appeal to upper-scale Millennials whose business is crucial to the store's growth. It's also part of a broader, long-term strategy to attract more upscale customers to 7-Eleven stores. Just last month, the chain began selling better-for-you snacks including organic trail mix.

Sure, 7-Eleven may be better-known for carrying $3.99 bottles of Yosemite Road wine, "but we have to take care of our more affluent guests, too," says Alan Beach, vice president of merchandising.

For the holidays, 7-Eleven will even be selling a $54.99 bottle of Stag's Leap wine at about 300 stores. Consider, an average bottle of wine currently sold at 7-Eleven costs about $6.

Behind the wine surge at 7-Eleven: changing generational tastes away from beer towards wine. Wine sales domestically have grown for 19 years straight, says the Wine Institute. Wine consumption grew 21% between 2001 and 2011, reports the Beverage Information Group.