The answer is 308.6, assuming you mean round it to the tenths place of course. :) The first digit to the right of the decimal place in any number is the tenths place, but if the number directly to the right of that is above 5, you must round it up. In this case, because it is 308.61, you need to round it down to 308.6
Edited because for some reason I read it as 306.61 instead of 308.61.