Your banker misinformed you. Not surprising in a time when everyone seems to be using the "Big Lie" system of politics.
If you make more than 200,000 net taxable income per year, and if you and the wife sell tthe house and make a profit of more than 500,000, and if you do not put the profit back into the new home, then, and only then will 3.8% be assessed on the excess of the 500,000.
Track this link: http://www.factcheck.org/2010/04/a-38-percent-sales-tax-on-your-home/