The U.S. economy had a net gain of 156,000 jobs in September, according to a report Friday from the Labor Department, which also says the unemployment rate increased slightly to 5 percent. The jobless rate rose one-tenth of a percent because more people started looking for work, although not all of them found jobs. U.S. officials count people as officially unemployed only if they are available for work and looked for a job sometime in the past four weeks. Economists say a stronger job market encourages people to resume their hunt for work and that can push up the unemployment rate. September’s job gains were lower than average so far this year; however, the data also show hourly wages rose 2.6 percent over the past year, growing slightly faster than the modest rate of inflation. The report shows 7.9 million Americans are out of work, a number that changed little in September. Another 5.9 million people are considered “under-employed,” because are working part-time, but want full time work. A positive report on the job market tends to help the incumbent political party, which is trying to convince voters that it has done a good job managing the economy. Bad economic news could help persuade voters that it is time for a change of leadership. This mixed report complicates the task of the U.S. central bank, which has kept interest rates at an exceptionally low level since the recession in a bid to boost economic growth. Many economists and investors expect the U.S. Federal Reserve to raise rates, slightly in December.