Site Settings
How do I add a charge for orders under a specific dollar amount?
To do this click 'Order Total Modules' under 'Site Settings'. Click 'Low Order Fee' and install it on your system if not already. Then press 'edit' and make sure you set the 'Allow Low Order Fee' to true. Then set the other variables to your preference and now an order fee will be appended to low orders based on your settings.