The minting of the Roman money supply was the responsibility of the Emperors. It could not be left to anyone else. There were 2 precious metal coins: the Aureus [gold] and the Denarius [silver].

Most transactions were carried out using the extensive range of Bronze and Copper coinage, which were produced in large numbers. The chief Bronze coin was the Sestertius.

 4 Sestertius equalled a Denarii, and
 25 Denarii equalled an Aureus.

Prices were variable, according to the local situation. Rome was an expensive place to live. [No change there then!]. A Sestertius would buy

1.6kg of wheat, or
a loaf and a bit;
a litre or so of cheap wine; or
2 goes with a whore!

It would cost someone

8 Sestertii to buy 40 litres of wheat in Egypt (enough for one person for a month)
4 Sestertii to pay the executioner to put a slave to death,
600 Sestertii to buy a ‘slave girl’ of not specially good reputation,
1000 Sestertii for a quarter hectare of reasonable farmland,
2500 Sestertii for an adult female slave, and
2000 t0 10,000 Sestertii for a reasonable tomb.

Compare these above prices with what you could earn.

4000 Sestertii a year as a soldier in the praetorian guard,
1200 Sestertii a year as a private in the legions, or
576 sestertii a year as a skilled worker in a mine, or quarry.