If you need to do redirect from urls without tail slash to urls with slash, you can simply add this lines in your .htaccess:
RewriteBase / RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-l RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_URI} !(.*)/$ RewriteRule ^(.*[^/])$ http://www.site.ru/$1/ [L,R=301]