is used mainly by school children, but adults use this less commonly in everyday conversations. Here's the list of possible expressions:
* : Typically used after work. This is only polite enough to say goodbye to your colleagues. Don't say this to important external guests.
* (): Typically used when leaving (and entering) an office, conference room, etc. You can use (without ) at the end of a phone conversation.
* () : Even more polite one with a humble form.
* : Very polite greeting, which is described elsewhere. It's unlikely that you hear this in a business setting.
And there are shortened forms: These are no longer considered as "polite", but are very frequently used, instead of , among colleagues who know well each other.