Improved customer service, cleanliness and quicker checkout times all helped results, said David Dillon, the grocer's CEO, during a conference call with investors and analysts. "Our very best customers are buying more from us," he says. "We're running better stores."

Kroger opened 16 units and renovated 39. The company also closed 36 stores, 16 of which are in the San Francisco and Sacramento, CA markets, which the retailer is exiting. The company currently operates 2,483 supermarkets and multi-department stores under more than 20 banners, including Kroger Marketplace, Ralphs, Fred Meyer and Food 4 Less.

Executives say that they are implementing aspects of their Fred Meyer mass-merchandise stores into the company's supermarkets. Best-performing categories for the company overall during the quarter were groceries, produce, natural foods and fuel.

Total sales for the quarter increased 8.2% to $19.4 billion, while earnings came in at $306.4 million, up from $294.3 million during the same year-ago period. Management also upped Kroger's same-store sales guidance for the year from 3.5% to about 4.5%.