Peru's currency is Nuevos Soles (S/.)
When traveling, as for small bills (billetes pequeños) for easier change. However, keep in mind that many Peruvians will not accept torn money.
Many places in Peru accept US dollars. However, if you want to exchange money, it's often faster and more convenient to exchange money in foreign exchange bureaus (Casas de cambio) rather than banks. They often also have better exchange rates.
Travelers in less trafficked areas of the world often find businesses that won’t take MasterCard of Visa. Peru offer an extra twist: Occasionally shops refuse these cards even though they display signs advertising them. Also, watch out for credit card fraud; as a precuation, inform your bank about your upcoming Peruvian vacation and then use your card wisely.
In general, Peruvians like their soles in small denominations. A fifty (roughly $20) is ok, but denominations of twenty and under are better to ensure merchants can make change.
That noted, Peruvians tend to put great stock in U.S. dollars, so even if you see an establishment doesn’t take credit cards and you don’t see an ATM, you may still be able to buy dinner. Make sure your U.S. currency is in pristine shape—many merchants and hotels will reject torn or overly worn bills.
TIPPING GUIDES & PORTERS
Tipping should be dependent on the quality of the service provided. As a good guide the tip is easy to work out per day of your trek, around $10-20 a day for the guide and $5-10 for the porters. This of course is an average and is also per person, but a good idea of what other people tend to pay.