In vaults beneath many of the large temples, secure within strong walls and constantly under guard, is where the rich people of Rome kept their valuables. When eventually the city began striking its own coinage, it was only natural that one of these fortified temples should be chosen to house the mint. In fact the Temple of Juno Moneta was the one chosen.
Over time, money and where it was minted, trade in general, and the entire economy were all encompassed in the single word moneta. The word still meant "warned" but now it also meant "money." The Latin language tends to do that. The word augustus, -a, -um, is another example. As an adjective it means "increasing," but after Octavian Caesar took it for his own name, Augustus, as a substantive noun, also started to mean "emperor" even though it still retained its original meaning.
So MONETA AVGVST could be short for moneta augusta, "the economy is increasing," which is a fine sentiment, except that it wasn't the message Domitian was trying to put out there, which was moneta Augusti, "the emperor's mint." The inscription MONETA AVGVST is ambivalent; MONETA AVGVSTI, with an I on the end, is not. Oops, hold that thought, because I'm getting a little ahead of myself here.
The Roman mint stayed in place in the Temple of Juno Moneta for some two hundred years until Domitian's reorganization of 83 A.D., when he moved coin production east across the Forum to a site near the Colosseum. There was no bronze issue at all that year. When striking resumed in 84 one of the two as reverse types was Moneta, the personification of the mint itself. This reverse type would continue to be struck uninterrupted until the end of Domitian's reign, making it his longest-running reverse type in bronze.
For whatever reason, at its inception in 84 the reverse inscription for this type read MONETA AVGVST. Somewhere in the middle of the following year, towards the very end of the Second Issue of 85, the inscription was switched to MONETA AVGVSTI (probably for the reason I have already suggested), and it remained that way until the end.
RIC 303 var is something of a curiosity. Here it is--
Note the date on the obverse, COS XI, not COS XI CENS POT or COS XI CENS PER. This coin is from the First Issue of 85, not the Second Issue or the Third. Here's the odd thing about it, check out the reverse inscription. MONETA AVGVSTI! So, if MONETA AVGVSTI was already in use at some point in the early part of 85, as by this evidence it clearly was, then why in the world did the mint revert back to MONETA AVGVST in the middle of 85? Hmm, curious, don't you think?
Next: I no longer feel like predicting, but the topic is going to be of some interest to somebody, I hope.