If you are manually writing the manifest and shipping to America . There is only one rate there is no discount other then the small business discount .
While if you use the online program you get a discount , depending on the volume you can get level 1, 2, 3, 4, 5 to America ground . Also get level 1, 2, 3, 4 across Canada
However the discount from 1 to 6 is pennies for the online program to America. In fact if compared to writing it with the manifest to America , you will find the savings little to slim
I would be interested to see were you get with CP