Box 2a is the taxable amount. On a rollover, you would not need a taxable amount. Here are IRS examples and more.
Box 5 is the difference between the gross and the taxable amount. The amount being recovered this year, See here.
Box 6 unrealized appreciation. See the rules here
Personally, I would keep the information in my financial folder in case an issue arises later and would probably leave the boxes blank. I don't know all of your details, which is why I included links just to be safe.
Reference: Instructions for Forms 1099-R and 5498
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