I've used TurboTax for about 18 years.
One of the features of TurboTax is you can see your IRS "profile" regarding the possibility of an audit after you complete your taxes each year. It gives you an estimate of your chances of being audited based on the income/expenses/personal information you entered for your return.
I would guess if you do that, based on what you've said, you would have a "low" risk of being audited or being "targeted."
If I was somehow in the wrong, do they give you a chance to pay the difference? Or is it straight to prison?
It's straight to prison if not the firing squad.
In my case they wanted an explanation of the income I showed on my return that they didn't have any information for such as a W-2 or 1099. It never got to the fines and penalties status so I can't really answer your question with any authority. Poodlebrain, who posts on this board, is a CPA and he can probably give you a very accurate answer.
However one year the La. State Department of Revenue lost my enclosed W-2's (before I started my own business and became self employed) and they wrote me a letter telling me I showed too much withholding on my state return and I owed them money for penalties and interest.
When I figured out they didn't include my state withholding from my W-2 I sent the "local" copy of the W-2 (which we don't have to use because we don't have a local income tax). I pointed out the "missing" withholding was on the W-2 and about 2 months later I got a letter from them saying "nevermind." I assume the IRS has some similar type procedures in place.