When I teach rounding to my class, I show them how we can round numbers to the 10 the number has or the next 10. I use a 0-99 board to show how it works. It makes sense to my class because we generally use a 0-99 chart and not 1-100 charts when we work on counting and place value.
As you can see from looking at the two boards, it is easier to see that we round numbers with a 0, 1, 2, 3 and 4 to the 10 the number has, and 5, 6, 7, 8, and 9 to the next 10.
Rounding on a 1-100 board. The 0 and the rest of the numbers that round 'down' are separated. If you split each 1-10 row in half (half to round down, half to round up - see my very straight red line!), than 5 will round down. This has confused my kids in the past.
I find rounding on a 0-99 board to be easier. The board is split in half vertically. 0-4 you round to the 10 the number has, 5-9 you round to the next 10. For example, 66 can be rounded to the ten the number has (60) or the next 10 (70). I ask my kids which one is closer and they can visually see that it is closer to the next 10 or 70. This way of talking reinforces places value too.
The same thinking can be applied to rounding to the nearest 100. This is part of the rounding board for my Monster Rounding game. It shows how you can round to the 10s (vertical line) and 100s (horizontal line). For example, if I had to round 782 to the nearest 10 or 100, I can look at this and it shows me.
Ok, so here's the freebie. I've done up a poster that shows how to round for 10s and 100s.
Click on the link or either pic to download.
I also have my Monster Rounding board game for sale on TpT if you are interested.
Hopefully you can use the freebie.