You'll need to combine CASE and GROUP BY, something like this:

SELECT CASE WHEN Total >= 0 AND Total < 100 THEN

WHEN Total >= 100 AND Total < 1000 THEN ...

END,

COUNT(Acct_no)

FROM Acct_sum

GROUP BY CASE WHEN ...

You don't state which side the boundaries fall into, so I've guessed - 0-99, 100-999 etc.

I'm sure you can work out the rest.

Cheers

Gaz