Lewis & Short

cor-rŏtundo (conr-), āvi, ātum, 1, v. a., to make round, to round off (postAug.).

  1. I. Prop.: cometarum corpus, Sen. Q. N. 7, 26, 2; 4, 3, 5; Petr. 39, 15.
    1. B. Trop.: enthymemata sua gestu velut corrotundant, Quint. 11, 3, 102.
  2. * II. Transf., of money (cf. rotundo, and our phrase, a round sum), to make up a sum of money: centies sestertium, Petr. 76, 8.