You count back from the decimal point (the dot) by one and that is your one decimal place.
Numbers 5 - 9, when rounded up add one to the number above them and they and all numbers behind them turn into a zero. e.g 56 rounded to the nearest ten will give you 60
Numbers 0-4, when rounded up do not add one number above them but yet they and all numbers behind them still turn into zero. e.g 54 rounded to the nearest ten will give you 50.
So number 6 when rounded up adds one to 7. Then 6 and 3 turn into zero
