Enigma 1533: Roman grid
From New Scientist #2696, 21st February 2009 [link]
Put one of the letters C, L, X, V, I into each cell of a 5 × 5 grid so that each row and each column is a valid five-letter Roman numeral less than 300. No numeral may appear more than once; the five horizontal numerals should be in descending numerical order from top to bottom, and the five vertical numerals in descending numerical order from left to right.
What is the sum of your 10 Roman numerals (expressed in ordinary Arabic numerals)?