I have Wells Fargo Bank here, and when I used my ATM card at Banamex or Bancomer in PV, it was not apparent to me that there were any significant charges. When I got home and calculated the exchange rate, it was 12.75 pesos per USD (last summer). My bank statement did not indicate any charges.
Ask at your local bank and they should be able to tell you.
Sally
Ask at your local bank and they should be able to tell you.
Sally