Absolutely, the Roman economy and system of labor was heavily monetized, and there is a decent amount of wage data surviving from the ancient world--in the Bible, for example, a denarius is referred to as a day's wage for a vineyard worker (whether this is accurate is another matter). Wages go back about as far as money does, or even earlier as before the practice of minting money laborers might be paid in standardized amounts of silver, grain, or other item. There is some debate about how widespread the use of monetary wages was--it was certainly standard in the cities but there were other models of labor in the countryside (such as tenancy or sharecropping). That said, there are enough examples of wages being paid for agricultural labor that it was at least present in farming.

It is worth noting, by the way that Roman soldiers were not paid based on campaigns, but were rather given an annual salary which might be supplemented by bonuses or booty.

The Roman economy was quite complex and sophisticated--they also had rent, fractional reserve banking, commodity futures trading and joint investment.

If you want to know more about the topic in general, check out Kevin Greene's Archaeology and the Roman Economy, which overviews these topics very well.