a sample of 100 daily journal transactions
this is to say there is 100 transactions, or there is a 100 day's transactions?
Is this to say, there are 100 transactions, or that there is a sample of transactions over a 100 day period?
"100" follows directly after "sample", so it means 100 transactions in total.
a sample of daily journal transactions over a 100 day period. Here, we don't know how many transactions, only that the sampling process covered the (daily) entries into a daily journal over a period of 100 days.