The Malagasy Currency is the Ariary (MGA)
There are ATMs in larger cities (Visa, VisaElectron, Mastercard), but it is advisable to take your cash in euros or dollars. It is easier to exchange cash locally on arrival at the airport or in big cities but ONLY at official exchange offices! Obviously the exchange rate can change, but nowadays the euro is preferred and exchanged at a better rate.
Even today, we find that prices are still said in the old currency, the Malagasy Franc (MGF), especially in the northern part of the country at markets or in local stores. Dividing this by five, you can easily calculate the amount to be paid in the ariary.