Why am I given an itemized total that is less than the total of the itemized items? Example: Total of all itemized deductions = $20K / TT says they = $15K

Itemized deductions do not count 1 for 1.  First, the total of all your state income taxes and property taxes is capped at $10,000, so any amounts over that are not deductible.  Second, only medical expenses in excess of 7.5% of your AGI count.  There are other potential limitations.  You have to count your deductible itemized expenses, not your raw amount.

Thank you for the reply. So you are saying that all of the items I entered and that are listed under tax breaks are not deductible?  

These are items that TT said are tax breaks.

I assume do, but I don't know what you are trying to deduct.  TurboTax sometimes gives misleading information about "tax breaks".