David J. Perry will be proposing a character set for Roman weights and monetary signs to Unicode in May.
More details, including the official proposal, are available on his site.
The glyphs on the right of this post are from his proposal. These glyphs represend the Roman signs for Sextans, Uncia, Semuncia, Sextula, Dimidia Sextula, Siliqua, Denarius, Quinarius, Sestertius, Dupondius, and As.
Some of these Unicode characters would be used on a proper encoding of the Historia Numorum, for example page 22. However, that page needs an additional 'hat' character. I don't think that character is defined anywhere in Unicode. I know its not in the Old Italic range. Maybe the 'hat' is an alternate glyph for some other character. I don't know Roman monetary symbols well enough....