Total existing-home sales nationwide slipped 0.2 percent in July compared to June and 9 percent compared to July of 2006, according to numbers released today by the National Association of Realtors. Single-family, townhome, condo and co-op sales stood at 5.75 million in July, down from 5.76 million in June and 6.32 million in July of last year, the association said. In the northeast, sales increased 1 percent from June to 1.02 million in July. The bump is still 2.9 percent lower than July 2006. Median home prices in the northeast for July stood at $290,900, up 5.9 percent compared to a year ago.