Impressive result of adding hundreds of dollars? (5,5)

I believe the answer is:

grand total

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'impressive result of adding hundreds of dollars?' is the definition.
I can't tell whether this defines the answer.

'impressive result of adding' is the wordplay.
'impressive' becomes 'grand' (similar in meaning).
'result of adding' becomes 'total' (I've seen this in another clue).
'grand'+'total'='GRAND TOTAL'

Can you help me to learn more?

(Other definitions for grand total that I've seen before include "Final result" , "Gold tartan - sum of all sums" , "Overall sum" , "sum, finally" .)

I've seen this clue in The Globe and Mail.

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