If you can get your hands on "Jefferson's Memorandum Books," edited by Bear
and Stanton, open to any page and you'll find cash transactions. The MB
starts in 1767. You can immediately look at GW's papers on the LoC site and
browse through his ledgers and account books, which use the word "cash."
http://memory.loc.gov/ammem/gwhtml/gwseries.html
Henry Wiencek