If a subsidiary book is miscast, (i.e. wrongly totaled), the account to which its total is posted in the ledger would show an incorrect amount whereas the individual accounts poted from the subsidiary book would total up to a different but accurate figure.
The Sales Book is under-cast by $1,000. The correct total is $79,400. (This mean that sales account in the ledger has been credited at $78,400 whereas the individual debtors have been debited with a total of $79,400 which is the correct total of individual invoices. As a result, the trial balance will show a difference of $1,000 with debit side having a larger total).
The Sales Book is over-cast by $100. The correct total is $36,400. (This means that the Sales Account in the ledger has been credited at $36,500 whereas the individual debtors have been debited by $36,400 in total. As a result, the trial balance will show a difference of $100 with credit side having a larger total.)