Several years ago, I started using a pint-sized milk jug with a screw-on lid to save change in my car. I put my savings from cents-off coupons, meal savings, the money I would pay for a meal if I take my lunch, or any other savings during the day. It fits in my cup holder. It is inconspicuous and easy to handle. If I need the exact change, no one realizes it contains money because it looks like it might be something to drink. When it gets full, I put it elsewhere and start over with the process.