Change tax on casio pcr-360 cash register

I have been programming the new tax in my casio pcr-360 cash register but the old tax could not be changed. i have done this before but i could not change it this time. can you please advise me on how to change the old tax to the new missouri 8.175% tax.
this is the procedure i am using:
3 sub total
0125 sub total
8.175 (new tax) ca/amt tend
5002 ca/amt tend
sub total

is this the right programming? thank you in advance for your help