This is a difficult question to answer exactly, because no two individuals tax situation is exactly the same.
From your question, it does not sound like your taxes will be complicated. Tax is not calculated on gross income, it is calculated on taxable income after all adjustments and deductions have been taken.
You will be filing as married, filing jointly. You will be able to tax deduct your mortgage interest and any medical expenses in excess of 10% (new percentage for 2013,) of adjusted gross income. This means if your AGI is $60,000, you will need in excess of $6,000 in medical expense to take the deduction.
As mentioned, an IRA would help. You each can put up to $5,500 each, but an $11,000 contribution might be a bit steep on $76,000 of income. You may want to see if you owe and then open an IRA with just enough to eliminate the amount you owe and get a small refund.
The tax on $76,000 is about $11,000, but again, you are not taxed on gross. The tax on $65,000 is about $8,800. This will give you a range on what your tax bill might be.
The recommendation of paying two years property tax on one year will not work in most cases as the lost opportunity cost on the money over time will be greater than the tax saved. I can explain lost opportunity cost later if you need an explanation. My recommendation is never give the government more than you have to in any one year.
You want to make sure when indicating withholding on the W-4 that you don’t have too much withheld. You don’t want the IRS holding your money all year. You can each select 1 and then when you do your taxes ask your tax preparer what he thinks the number should be. You can always change the withholding amount and also indicate an additional amount to be withheld in necessary.