How do I determine the amount to pay for the CARES Act (section 2302) deferral? The amount I declared in Schedule 3 is different from the form I got from the IRS.

The amounts are "close" but the amount I put on schedule 3 line 12e was a nice round number, the amount the two IRS-suggested payments add up to is a little less.  Also, TurboTax says it's supposed to be half this year