After hitting rock bottom rates of under 5 percent this year, Freddie Mac has predicted mortgage interest rates will rise steadily throughout 2010. “No one should have expected mortgage rates to remain under 5 percent, so the only way to move is up,” Lawrence Yun, chief economist with the National Association of Realtors, told CNBC. Yun predicts mortgage rates will hit 5.7 percent towards the end of next year. But, he said the looming expiration of the first-time homebuyer tax credit will spur sales and prices will rise in the upper single digits during 2010. Matt Garrison, managing director of the Matt Garrison Group, however, had a more negative outlook for the housing market next year. “The best case scenario is flat to anemic growth in home prices and the worst case is another 5 to 10 percent downslide,” Garrison said.