Dial Plan Suffix

How can I add a character to the END of a dialed number.

This would be like adding 99+NXXXXXX to get 99NXXXXXX dialed out, just on the end such as:NXXXXXXX+99 to get NXXXXXX99.

I already add stuff on the front... but need to add stuff at the end.
Think of this as a dialed number sandwich :-)
This would ONLY be in one outbound route and would not be on all dialed numbers.

Any thoughts would be appreciated.