Number sense seems to be a challenging concept for children with a disability in math. Rounding would seem a very useful tool but understanding how to round and visualizing whether to round up or stay the same can prove to be very difficult.
One thing that is important is to use consistent language while teaching the method of rounding.
Here is one example:
For some students I found consistent language and methods were not enough. This cup was an effort to make the concept visual. If the number is over five, the cup is closer to being full. As you can see, the cup was used a lot!