If I'm just going to a random branch at my lunch break I'll clean them out if they have any. They usually don't have any more than a $100 worth but they're usually happy to give you them even if you're not a customer there. If I'm going to my bank I order the $500 sealed box of 50 rolls. Frequency varies, sometimes you'll buy $40 worth of rolls from a bank and find a silver right away, and sometimes you'll go through an entire $500 box and find nothing.