Automatically charge tax on shipping

Automatically charge tax on shipping

When we do a quote we charge tax on the subtotal cost, but when I put in shipping I have to manually select a tax amount. 

How do I have it automatically apply tax to the shipping as well?

I have provided a screenshot that shows I have to manually do this. Seems odd its not an option as our sales staff keep forgetting to do it and it's costing us money.  Surely I'm missing something.