A few years ago I had a student who was 2-3 years behind in math. He stretched me as a teacher to find solid ways to model what we were doing in fourth grade.
When we got to rounding decimals, it was clear he wasn't sure about rounding even to the nearest ten. I have a stack of hundreds charts I use for math stations, interventions, etc. I grabbed one and used it to show him the pattern for rounding.