Display menu Shopping cart (# items) and total amount
You can use https://www.drupal.org/project/menu_badges to accomplish that.


  Once enabled, go to Administration > Structure > Menus, and click
  "list links" next to the menu containing the target item. Click "edit"
  next to the item and select the badge to display with the Display Menu
  Badge select box.


Or you can set the parent menu item of the Shopping cart (# items) link provided by the cart module to your menu. This menu item is provided by commerce and by default can be found in the navigation menu at admin/structure/menu/manage/navigation