Rounding Anchor Chart. Like the little monster! He could be a mascot :)
I also have my students underline the place value being rounded, but I also make them box the number that tells them if the number rounds up or stays the same. 5 or more, raise the score. 4 or less, let it rest.
Rounding anchor chart
Rounding Numbers, rounding coaster; I saw a fab teacher at BCE demonstrating this concept!