How does this look?

def main() : print ("Bram's Postage Rate Calculator V 3.0") print ('Please complete the following questions below!')

Location Input

location = input('Is your destination country Canada or the USA? (Case Sensitive):')
if location == "Canada" or location == "USA":
    print("Thank you!")
else: print("Error: destination must be Canada or USA")

Mass Input

mass = float(input('How much does the package weigh in grams? It may not exceed 500 grams in mass: '))                                                   

Size Input

envelope = input("Is your envelope a standard size? Y/N: ")

Conditional Structure

if mass > 50 and envelope == "Y" :     
    envelope = "N" and print("The envelope size has been changed to non-standard due to the mass")

if location == "Canada" :
    if mass > 30 and mass <= 50 and envelope == "Y" :
        postagerate = 1.10
    elif mass <= 30 and envelope == "Y" :
        postagerate = 0.63
    elif mass <= 100 :
        postagerate = 1.34
    elif mass > 100 and mass <= 200 :
        postagerate = 2.20
    elif mass > 200 and mass <= 300 :
        postagerate = 3.05
    elif mass > 300 and mass <= 400 :
        postagerate = 3.50
    elif mass > 400 and mass <= 500 :
        postagerate = 3.75
if location == "USA" :
    if mass > 30 and mass <= 50 and envelope == "Y" :
        postagerate = 1.34
    elif mass <= 30 and envelope == "Y" :
        postagerate = 1.10
    elif mass <= 100 :
        postagerate = 2.20
    elif mass > 100 and mass <= 200 :
        postagerate = 3.80
    elif mass > 200 and mass <= 500 :
        postagerate = 7.60
print('Your total shipping charges are equal to: $',postagerate)

main()