A seesaw start for stocks ended with a rally Friday, as traders decided that a healthy job market mattered more than the Fed scaling back its economic stimulus. After the government reported strong hiring for June, traders and investors struggled over how to react. At first, they pushed stocks higher because the news was better than expected. Then they drove stocks lower because improved hiring made it more likely the Fed could ease back on its bond buying. Relatively few shares changed hands Friday because many traders were still on vacation after the Fourth of July. Light volume may have contributed to the market’s early volatility.