How can add trailing slash if I have two or more subdirectories ?

[Sputnik]

Problem to add trailing slash if I have two or more subdirectories 

rewrite ^/([^.]*[^/])$ $1/ permanent;  //this is working example if I
have one directory

http://example.com/foo/ (with trailing slash, conventionally a
directory)
http://example.com/foo (without trailing slash, conventionally a file)


How can add  trailing slash if I have two or more subdirectories ?

http://example.com/foo/foo2/
http://example.com/foo/foo2

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,223360,223360#msg-223360