Is the software calculation of Taxable Income $114,199 multiplied by 13.8% Blended Tax Rate equal a Tax Liability of $15,739 (I calculate $15,759), is this correct?

The blended tax rate is not used to calculate your tax. Taxable income is not all taxed at the same rate. Depending on your types and amounts of income, the calculation of your tax can be somewhat complex. The blended tax rate that TurboTax shows you is just meant to give you a rough idea of your total tax as a percentage of your income. It's just informational.

TurboTax calculates the blended tax rate from the amounts of income and tax on your tax return, after your tax has been calculated as specified in the tax law.