I recommend entering in all of your deductions even though you have already reduced your liability to zero.
There are a few reasons why. First, if the IRS ever questions any of your deductions and lowers them, having the additional unused deductions already on record can help keep your tax liability at zero. Second, your state might have different rules or lower limits, so including everything may benefit you on your state return, if your state allows itemized deductions. Finally, some things like charitable donations or investment losses can be carried forward to future years.
