Is 2018 Fed tax due on 1040 line 10 income of $62,227.00 (joint return) $4,704 (your calculation) or $7,086.00 (my calculation)?

It depends on the source of the income. Some income is taxed at ordinary income tax rates and other income such as qualified dividends and long term capital gains is taxed at lower tax rates. How did you calculate your amount?

The $62,227.00 of line 10 taxable income includes$19,854.00 of "Qualified dividends"

The $19,854 of qualified dividends are taxed at 0% since the total taxable income is less than $77,200 which is the maximum for 0% tax on qualified dividends and long term capital gains. The tax on the remaining taxable ordinary income of $42,373 is $4,704 according to the IRS tax table for married filing jointly. The TurboTax calculation is correct. 

Thank you, very much. You have effectively banished my fear that I seemed to be paying too little  in taxes!