The try and in “try and tell the truth” is a different idiom from “[try] and [x]” as two separate actions. It can almost always be replaced with “try to”.

For example, in “let’s try and finish this” it does not mean trying then finishing, it is try to finish. The construction is more obvious in a phrase like “try and stop me”. This phrasing is very common in movies, it might just not be as popular in your area.