A report is produced weekly of the cash transactions from $3,000 - $10,000, for the previous three weeks. It is used in a review to determine any indications of structuring. If such an indication is found, a SAR is filed and all the appropriate supporting documentation is kept for five years.

Is it necessary to keep each weekly report for those five years?

I generally keep them from exam to exam so as to support the fact that the review is done. They don't seem to serve any meaningful purpose after that time period.

Unless you list them as supporting documentation, that should be more than adequate.