Currencies in The Matrix

While rewriting my background, I wondered if what currency was used in the Matrix from a Bluepill perspective? Furthermore, would there be more than one currency?

 I would imagine that the Bluepill currency would just be $. Other suggestions welcome.

Whether there is more than one currency depends upon the existence of other areas. If the Machines modelled Megacity on the late 1990's, did they make the simulation complete enough for Bluepills to think that there are other countries even if there is only one Megacity? Or did they just leave it as Megacity being the only city in existance in the mind of the Bluepills, and not bother adding in the illusion of other cities/countries for the Bluepills to believe in?

Answers to the above questions, or even a debate about the answers, will be gratefully recieved. 

the articles on Neo's computer screen definately acknowledge that the blues are aware of a wider world than just their city... but in terms of realism, I can only imagine the blues using us dollars, unless they were supposed to be from outside the country (a sentinel message on Caboclo mentions that he was given fake memories of growing up in south america)

Funny this thread is up, but what kind of currencies are used while in the real?  Do they use a trade format or some kind of money?

I think that zion would exist solely on barter, or work as a planned economy laid out by the council.