The parent company of T.J. Maxx and Marshalls said July same-store sales rose 7 percent, topping analysts’ forecast of a 5 percent gain, as more shoppers came into its stores. Framingham-based TJX Cos. cited higher sales and profit margins in raising its forecast for second-quarter earnings to 55 cents per share, from 53 cents. For the year, TJX expects to earn $2.38 to $2.44 per share. It said customer traffic rose ‘‘substantially’’ at all its chains, accounting for most of the increase.