u use the closest number to the number u are rounding up to round it up.if it is 0-4 u round it to 0and add to the number while if it is 5-9 u round it up to 1 and add to the number.after all rounding up the number used to round up downwards will be converted to 0s
If the ones place has a number less than 4, the tens stay the same with a zero in the ones place. If the ones place has a number more than 5, the tens will have another ten. If the ones place has a number 5 in the ones place, then you round the tens to the next ten.