[English Grammar] Altogether & All together.

From Grammar Paranoia 

‘Altogether’ means ‘completely’.

My new house isn’t altogether finished.

‘Altogether’ means ‘everything considered’.

Altogether, she decided, marriage was a bit of a mistake.

Altogether can also be used to give totals.

That’s $4.39 altogether.

I’d like three dozen altogether.

All together usually means ‘everybody/everything together’.

Come on, everybody sing. All together now…

Put the plates all together in the sink.

They all went to the cinema together.

SWAN, Michael. Practical English usage. Oxford: Oxford University Press, 1991.