=SUBSTITUTE(A2;RIGHT(A2);IF(RIGHT(A2)="3";"5";IF(RIGHT(A2)="4";"5";IF(RIGHT(A2)="6";"5";IF(RIGHT(A2)="7";"5";IF(RIGHT(A2)="5";"5";"9"))))))
This is good as I can get it; however its not quite right as it will change 630,631,632 to 639 instead of 629. I cant figure out how to correct it; but...