This was one of the things that he liked about Maddox, the man wanted to know what he was getting into and Octavius loved to explain. He was sure that if he ever gave up the shop, he'd want to go into teaching about Divination. Of course his practices might go outside the realms of the magical world and get him in trouble.
"It's rooted in many things: Money and silver have both been used with magic for generations. In folk magic, images of money are often used in spells to draw more money or a "lucky" coin is carried to attract financial good fortune. Silver coins in general have been popular in magic in Europe since the medieval times. And it's not even just with magical folk. There is a near universal acknowledgment of silver as having magical properties. And dimes having been made of silver at one point were drawn into that. If you wanted a hoodoo bag for instance, a suggested combination for protection is 9 silver dimes filed down in a nation bag."