While rounding numbers on your tax return to the nearest dollar is okay, rounding to the nearest thousand is not -- especially when itemizing deductions like business expenses, unreimbursed employee expenses and job hunting costs.

If you submit figures like $5,000 in auto costs, $2,000 in gas mileage and $4,000 in lodging, it may look like you pulled those numbers out of thin air or inflated them by rounding -- since it's unlikely that every single expense was a perfect multiple of $1,000.

Related: 3 ways to lower your tax bill

"Having a return with a lot of zeroes on it may be a cause for a return to be pulled," said Lieberman.

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