The IRS requires any business that receives more than $10,000 in cash or check payment from one customer, either in a single payment or series of connected transactions, must file Form 8300. This is part of their anti-money laundering (AML) program. 

The 10k Report has been added to help you comply with this. The report allows you to specify a dollar threshold and choose a date range. Any customers whose total tender exceeded the threshold will be displayed along with their payment details.