The monetary unit is the peso. Centavos still exist but one wonders why they bother, as they are meaningless now what with $11+ pesos to the U.S. dollar at this writing. You can forget the centavos frankly, as inflation has rendered them useless. Consider that it takes one hundred centavos to equal one peso, and eight pesos (800 centavos) to make less than a Canadian dollar.
Actually since November 1996 the pesos was allowed to float on the money markets and after Chicago closed out a large short sell in early 1996 it tended to stabilize at roughly $5+ for CDN$ and $7+ for the US$ and stayed relatively steady through all of 1997 until the Asian flu upset world markets and the Canadian dollar lost a dime to the U.S. The pesos faired even worse in the late summer of 1998 where the US dollar claimed over ten pesos, and the Canadian garnered a high of 6.3. It has since climbed a bit more to just over $11 pesos for the US and almost $10 pesos for the Canadian dollar now in 2007. This means that MEXICO in 2008 should enjoy a bumper year of tourism at the expense of Florida and Hawaii.
What to take with you? Anyone traveling anywhere should carry at least 20 one dollar U.S. bills with him/her and maybe three twenty U.S bills as well. Sixty to one hundred American dollars in small bills is ideal. That’s all the cash I carry on me usually, the rest is in U.S. or Can. Traveler cheques. Currently U.S. travelers cheques yield more pesos even after a double change so the argument of what to take is academic presently but that might change with a dramatic decline in the CDN$ (Remember where you heard it first). In that instance, I would take Canadian when I’m just going to Vallarta and take U.S. if going to other destinations in Mexico where the Canadian dollar is not so well accepted as it is in a resort city like Vallarta.
The smallest common bill is a $20. peso note, followed by a fifty, one hundred, two hundred and a five hundred note. Coins like the new “tooney” introduced in Canada made of composite bronze and silver/nickel alloy come in one peso, two pesos five, ten and twenty. A fifty pesos coin (currently worth $6 CDN.) exists but is not circulated much, as it is like silver dollars, they tend to hoard them. This was bound to change as it used to take forever to count five hundred dollars into Mexican currency. (Another good reason to change with the desk).