In such phrases as "all-round man" and "all-round athlete," this hyphenated adjective is preferable to its twin, all-around. In this sense, round provides the idea of completeness or fullness, whereas around suggests position with relationship to a center. By this reasoning, one should say "The dog walked around the chair" rather than "round the chair." Neither all-round nor all-around (both adjectives) should be confused with all round and all around (two adverbs): "Jack walked all around the waterfront."
Dictionary of problem words and expressions. Harry Shaw. 1975.