Q. When undercharged by a Gentile cashier in a Yiddishe store, is one obligated to go back and pay them as soon as possible? Does it make a difference how much? Can one simply assume that there was some discount that one was not aware of?
A. Horav Shlomo Miller’s Shlit’a opinion is that one should give a call to the owner, describe the issue and ask him what he wants him to do.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a