So I arrived with my rental in Verona and it turns out that you need coins to pay for parking. What is the best way to exchange bills to coins? At 1€ an hour 14 hours a day I need a bunch - not just what you get from buying coffee with 10€ bills.
Enter a bar or supermarket and ask if they can change your 10€ bill into 1€ / 2€ coins for the parking. Repeat again in some other place. Probably they will stare badly at you. You're not obliged to consume or buy anything. Be warned that some cashiers may refuse your request.
This is a common behaviour even for italians.
This site reports that parking meter accept "bancomat" (debit card). An alternative would be to buy a pre-paid Verona Park coupon.
Look for unmanned automatic laundry places. Since the washers/dryers there are usually coin-operated, you'll find a coin dispensing machine to convert your notes into shrapnel. You're likely to also find similar machines at self-service car-washes, or in any other business providing coin-operated services. They usually look something like this:
Cassa per lavanderia a gettoni self service, LAVATU, Fair use