Costco's ( COST) second-quarter earnings fell 3% despite an 11% jump in sales, as a gain in the year-ago period hurt the comparison. Costco earned $296.2 million, or 62 cents a share, in the quarter, compared with $305.5 million, or 62 cents a share, a year ago. The year-ago period had a $52.1 million tax-related gain. Sales were $13.78 billion in the latest quarter, up from $12.41 billion a year ago, while same-store sales rose 7%. Analysts were expecting earnings of 60 cents a share on sales of $13.79 billion in the latest quarter, which ended Feb. 12. Costco also reported its February sales Thursday, saying same-store results rose 8% from a year ago while overall sales rose 11% to $4.21 billion for the four weeks ended Feb. 26. The stock closed at $52.19 Wednesday.