No one here will be able to give you a perfect answer because we don't know what "witholding election" you made on your Form W-4.
There are multiple payroll taxes, the most common of which are:
Social Security: This year, temporarily reduced to 4.2% - Your boss also pays another 6.2%
Medicare: You pay 1.45%, Your employer also pays 1.45%
Disability: Depends on the state you are in, in my California, we pay 1.1% towards disability.
Federal: Varies according to what you put on your W-4.
State: Some states have no tax, others vary according to what you put on your W-4.
So, for someone making $1,280 a month, you would pay:
SS (1280 x 0.042) = $53.76
Med (1280 x 0.145) = $18.56
Dis (Depends on your state rate, in Calif = 1280 x .011) = $14.08
Fed = Total annual income will be $1280x10 = $15,360. If you have no children and are single, you'd take out about $9,400 for standard deduction and personal exemption and pay 10% on the rest. So, $15,360-$9,400 = $5,960 taxable income. x 10% = $596. divided by 12 months = $49.67 per month.
As you can see - the federal and state taxes really vary, because if you have kids, or qualify for special college credits, etc.. then your federal tax will really change. I hope this helps!