Please read this TurboTax FAQ on how to report your cryptocurrency transactions:
https://ttlc.intuit.com/replies/6468652
Partially helpful, thanks. The software only asks about sales, and then about cost basis and date of purchase. Often I made multiple small purchases over the course of days or weeks and then one big sale, so I can't enter a single correct date of purchase. Is there some other way I should be entering purchases separately and individually?
Look at Form 8949, where each and every "capital" sale is listed out:
https://www.irs.gov/pub/irs-pdf/f8949.pdf
and you'll see that there no detail information about the basis of what was sold listed; all that's entered is a summary number.
So, assuming that all your "lots" of crypto included in the sale are the same "term", (long term or short term), you can simply compile the detail outside of TurboTax and enter the total basis of the crypto sold and enter the word "various" in to date acquired field. Of course you attach this compilation to your paper copy of your "as filed" income tax return, (that you keep in a safe place), so you can prove to the IRS that you've entered the correct figure, if they should ever ask.
Tom Young