I sang at 2 paid church services at my local church. The issue is that instead of a check, I was paid in cash for both events at the same time. As a result, I have no way of looking into my bank statement to see how much I earned on those 2 events. I think it was about $400 or so but I cannot remember the exact amount due to the fact that I did not receive a check to deposit. I know this income is taxable, but I may be in trouble if I cannot remember exact amounts. What should I do if I cannot remember exact amounts?