TurboTax appears to have computed the wrong tax (line 44)

My Taxable income is 68254. So I'm in the MFJ 15% bracket. The tax i should pay is 9311 (68254-18550=49704x15%=7456+1855=9311). TurboTax computed the tax at 9314. Why is this different? And should TurboTax refund me that $3? That's a difference of $20 taxable income. I know it's not a big number for me, but people using this that have much higher income than me could have a much bigger consequence.