Since you are asked to round to the nearest hundred, you should first locate the 100's place which is shown underlined in red below.
Next you need to determine if you will round down to 68800 or round up to 68900. This depends on the digit immediately to the right of the place value you are going to round. If this digit is 5 or higher, you round up. If it less than 5 you round down.
In this case, since the digit to the right is 1 we round down to 68800