If you click this link:
https://www.santander.com.ar/banco/...v44+campos+texto.pdf?MOD=AJPERES&CVID=oQY1DEZ you'll open a PDF, look for "Operaciones en Caja (Todas las Cuentas)" and you'll see zero commission for any type of Peso transaction at the cashier's desk.
I thought it was a strange question, I've never been charged anything to make deposits to other people's accounts, and any bank I've gone to, so I had to look it up to be sure.
Did you just claim the prize for resurrecting the oldest zombie thread on the forum?