Does the 'income tax paid' section of TT supposed to add up to all income withheld (fed, SS, med) across all W2s or are certain withhelds left out?

[AnthonyC]

It only summarizes the income taxes paid which does not include Social Security and Medicare taxes.  

If you scroll down past the Tax Breaks page on the Deductions and Credits screen to the Estimated and Other Taxes Paid.  Click Show More.  Then select Income Taxes Paid.  You will see a blue link that will give you a breakdown of the actual number.  See screenshots

While it shows under Deductions and Credits, it’s actually just a summary number and not necessarily related to any particular deduction (some of it is not even a deduction - i.e. federal taxes withheld on your federal return).