Cant get tr command to generate ROT5 or simple gematria

[outboundessentialconnection]

So I can't understand why I can't get tr to output ROT5:

01234
56789

tr '0-4' '5-9' <<< 47 = 97 not 92 ?


Also when trying to do Simple Gematria where each letter of alphabet is 
equal to A=1 and Z=26. I can't get this to work:

tr 'A-Za-z' '1-26' <<< coreutils = 666666666

When it should be 122

is this cause tr is limited to 0-9 and cant do double or triple digits?

Could support for double or tripple digits be added?


Thanks