TurboTax's numbers are correct because for taxable amounts up to $100,000 one is required to use the Tax Table which produces taxable amounts based on $50 increments of income in the ranges that you are testing (except for $520,000 where you actually see agreement) and the tax is based on the midpoint of the step. If you add $25 to each of your income amounts you should see agreement. In other words, where there is disagreement the error is in both your spreadsheet result and in the result from SmartAsset.
Also, in your spreadsheet, use TRUNC((income-deduction)/50,0)*50+25 in place of income minus deduction when income minus deduction is $100,000 or less. (This won't be quite right at lower taxable income amounts where the table uses $25 income steps.)
