A North Philadelphia man with two prior armed-robbery convictions has been held for trial on murder and related charges in the March 3 shooting of the owner of a neighborhood check-cashing business.Eric Locke, 32, was held by trial after a preliminary hearing this morning by Philadelphia Municipal Court Judge David C. Shuter on charges of murder, conspiracy, robbery and various weapons counts in the death of 53-year-old Joel Blumer. Police allege that Locke was the gunman who accosted Blumer minutes before 9 a.m. on March 3 as Blumer, of Holland in Bucks County, prepared to open his B&R Check Cashing store at 26th and Sterner Streets.