I was in Santiago Chile just recently and the terminals there are all over the place. It doesn't present the transaction as USD vs local currency, it just shows an upcharge amount for the card being "foreign" and asks if you want to accept it. Anywhere from 2% all the way to 11% depending on the bank terminal and transaction amount. Some larger stores didn't charge it but I ended up paying cash a lot.

Also the ATMs charge nearly $8 USD (7000 peso) transaction fee for each transaction, even in local pesos. Luckily schwab reimbursed it but its definetly higher then I've seen in a lot of places.