Really no way to do what you are asking if an alternative route is not presented. Waze is designed to take you via the fastest route with the current conditions. There are other factors to the routing such as road type, distance, etc.
So likely the way Waze is taking you is the fastest route. If you want more control of your route and the fastest route is not that important, another App may suite you better.
There is toll road avoidance in the options. It's not sophisticated enough to allow the cost to be factored in. And not very helpful if you area has many toll roads.
San Diego, California USA and Tijuana, Mexico
iPhone 6s Plus, iOS 9.2.1, Waze 4.1
Waze - PLEASE ADD CARPLAY SUPPORT