I can tell you the mistake I made.
I already knew what my total cash contributions were--fully supported with all the documents to get through an audit if necessary. So I simply recorded that figure directly to the form.
It turns out TT won't let you do that. Even though the IRS return form does not ask for the detail, the only number TT will accept is the one that comes from entering each one—one by one. Lesson learned. The IRS trusts us but TT doesn't. :(
TT also likes to sell its "It's Deductible" program, so there's that.
