The Argentine unit of currency is the peso (AR$).
Carrying cash and an ATM card is the way to go in Argentina.
In restaurants and cafes it’s customary to tip about 10% of the bill for decent service. An interesting note: when your server is taking your bill with payment away, saying ‘gracias’ usually implies that the server should keep the change as a tip. If you want change back, don’t say ‘gracias’ – say ‘cambio, por favor’ instead.
Note that tips can’t be added to credit-card bills, so carry cash for this purpose. Also note that the cubierto that some restaurants charge is not a tip; it's a sort of 'cover charge' for the use of utensils and bread.
Bartenders they don’t expect a tip, but it's OK to give a small bill for a drink or good cocktail.
Bus porters a small bill
Delivery persons a small bill
Hotel cleaning staff Ten pesos per day (only at fine, upscale hotels)
Hotel porter a small bill
Restaurant servers 10%; 15% for fine restaurants with great service
Taxi drivers no tip unless they help with luggage; many people round up to nearest peso
Tour guides 10% to 15%