In settings -> URLS - [Use URLs with trailing slash]

If this dropdown is set to: Always use URL's with trailing slash.

A trailing slash is added to any URL not making any difference to URL's that end with file extentions!

EG: http://myurl.com/example.aspx => http://myurl.com/example.aspx/

Url trailing slashes are intended for directorynames not for actual filenames.

I came across this because my rewrite rules do make a distictin between files and folderpaths. My rewrite rules didn't work correctly since Kentico changed a filepath to a folderpath!