Really did not know that...
Totally impractical for most folks to track, but good to know.
Actually it’s not bad...the IRS, believe it or not, has an easy way to do it. You give their site some basic info - such as income, number of kids, zip code (to factor in local taxes) and they give you their estimate of what you paid in sales tax...which can be up to several thousand dollars. On top of that, if you have a ‘big ticket’ item, like a car, you get to tack that on to the above, possibly doubling the deduction.
You do still have the option of collecting receipts and adding them up, if you think you may exceed the IRS number (maybe by furnishing a house with high-end stuff, for example).
...and the best part - this deduction only works in red states, that is states without an income tax...as you can only take one deduction or the other (either sales or income tax, but not both), and income tax just about always wins in blue states - so they never get to use the deduction.