here's the rounding (up) function, to be placed after the loop function in the sketch:

int Ceiling(int input, int ceilTo)
//input is the integer number to be rounded
//ceilTo is the desired rounding (up) value
{

   if ((input % ceilTo) != 0) 
    {  
        return ((int)(input / ceilTo) * ceilTo) + ceilTo;  
    }  
    else  
    {  
        return (input);  
    }  
}  

After the sensor input is read in the sketch, e.g. light level, insert the line

lightLevel = Ceiling(lightLevel,10);

Rounds all light level values upwards to the nearest 10. Depending on your rounding value, this will reduce the number of times the sensor sends an update to the gateway since updates are only sent when the value is different from the one previously sent.

porting of insignificant light level changes to the gateway (which would be especially important on battery power). Will provide the code if any interest.

Hey @Dan-S. I would be interested in seeing the code - so yes pls!

Have you seen used the MAP function in arduino?
http://arduino.cc/en/reference/map
I think it might do the same as what you are wanting to do....

Cheers,
Greg