My principal's wife who teaches fifth grade shared this with our fourth grade teachers to help students learn how to round. We have used this rap with great success when teaching rounding and estimating. I usually make each student an individual copy to keep in his/her math folder plus I have a poster sized copy on my wall.
Find the place value and circle that digit.
Move to the right and underline get it.
0-4 Cirle stays the same.
5-9 Add one is the game.
Now, flex your muscles like a hero.
Digits to the right change to zero.
All other digits remain the same.
Yo! You're a winner in the rounding game.