If that works out well we can move on to publishing all transactions over a certain threshold (over a certain timeframe so you can't split the transactions). And publish all transactions that go to certain countries on black or grey lists.
Limiting cash transaction is a okay thing be there's much bigger fish to catch, if only politics meant it seriously.
Salaries are the most important transaction to monitor as they represent a recurring expense and easily become inflated in the government sector.
Tax payers have a right to know what they pay for and how much it costs. What reason are you using to justify publishing private transactions?
My view might be biased as I live in Austria which is well-know for government subsidies and funding. And that includes gold handshakes to send 50 yr-olds into early retirement. WHY THE FUCK!?!
Anyways, my point being: Instead of outlawing big cash payments (hard to achieve in my eyes) the government has a lot of opportunities where it can show the transparency needed to re-establish trust from the plebs (sorry, citizens).
I'd see publishing public transactions as a first step and private ones as a second step. I mean, all we know about that dutch-irish sandwich is fairly limited, but if those transactions had been public early on some data scientist would have said "oh, that looks funny".