What did the romains use for currency?

Answer 1

Coins, just like today.

Salt was also used, as Rome's major highway was called the Via Salaria (Salt Road): along that road, Roman soldiers transported salt crystals from the salt flats at Ostia up the Tiber river. In return, they received a salarium or salary, which was literally money paid to soldiers to buy salt. The old saying "worth their/its salt" (to be valuable) derives from this custom of payment during the Roman Empire.

Read more: What_did_ancient_Romans_use_for_money