I changed the interest income on a return by $8 and the increase in federal tax was $11, which doesn't sound right.  I manually calculated with the 2018 Tax Rate Schedules and there was a discrepancy. The increase was only $2, not $11.

Taxable income                                                        $53,199          $53,207     increase $8

Tax calculated per Tax Rate Schedule                       $7,643           $7,645      tax increase $2

Tax calculated per  Intuit ProConnect Tax Online      $7,638           $7,649      tax increase $11