Funny story here about his being audited in the late 50s. Two IRS men came to our dairy farm to audit his tax records. They questioned some tiny deduction for feed. He went to the cupboard and pulled out a paper sack, dumped it and plowed through the receipts until he found it. They didn't ask again. He even got more money back for the years they reviewed. I keep everything that the IRS might possibly want to see and then some.
I had a similar situation. Was called in for an audit after I wrote a letter to Bill Clinton, telling him what I thought of some of his policies, back when he was president-- (don't tell me THAT was a coincidence...). Once the IRS examiner saw that I had detailed records for every bit of income and expenditure, she pretty much concluded the audit and said I didn't owe any more money. They won't waste their time once they see that you have kept good records.
It's a shame we have to spend so much of our life doing that, tho!