$s = "The\tquick\tbrown\tfox\tjumps\tover\tthe\tlazy\tdog";;

print $s;;
The     quick   brown   fox     jumps   over    the     lazy    dog

($t=$s); 
1 while $t =~ s[(\t)]{ '.' x ( 8 - ( $-[0] % 8 ) ) }e; 
print $t;;
The.....quick...brown...fox.....jumps...over....the.....lazy....dog