Look at the first digit after the first non-zero digit; if it is 5 or more, add one to the first digit, otherwise keep the first digit as it is; replace all the digits after the first digit by 0s....
"Tag! Your it!" you would be "it" one round. Or "Got you!" and they ask you when you were "it" and you say "I was it in one round." really they both make sense.