Autozone Inc., the largest U.S. auto parts retailer, (NYSE:AZO )said Tuesday third-quarter net income rose 5 percent due to better sales and greater efficiency.

Net income increased to $151.6 million, or $2.17 per share, in the quarter ending May 5, from $144.4 million, or $1.89 per share, the same period last year. Sales rose 4 percent to $1.47 billion.

Analysts surveyed by Thomson Financial forecast earnings of $2.15 a share, on average.

The company said its gross margin as a percentage of sales was up slightly to 49.9 percent, from 49.7 percent a year ago. It says the improvement is a result of initiatives to improve its category management and reduce its supply costs.

The firm that sales at domestic stores open for more than a year - a key retail metric - rose 0.4 percent in the quarter.

While we experienced disappointing sales in the first half of April, we were pleased to deliver 15.0 percent growth in earnings per share for the quarter, said President and CEO Bill Rhodes.

During the quarter the MemphisTenn- based company opened 33 new stores and replaced five stores in the U.S. Additionally, it re-opened one of the remaining two U.S. stores closed due to hurricane-related damage in last year's first quarter.

Shares of Autozone fell 89 cents, or 0.66 percent, to $131.42 in afternoon trading on the New York Stock Exchange.