Richmond-based used car dealership chain CarMax Inc. said fourth-quarter profit rose 13 percent as improved inventory and financing offers drove up sales. CarMax, which operates more than 115 stores, reported earnings of $107.2 million, or 46 cents per share, compared with $95 million, or 41 cents, a year ago. Revenue rose 13 percent to $2.83 billion. Analysts expected 45 cents. “We feel pretty good about the way we’re executing our business right now,” CEO Tom Folliard said.