double d = 551425.451078772;
int i = (int)Math.Ceiling(d);
If you want to round to the nearest int:
int rounded = (int)Math.Round(precise, 0);
You can also use:
int rounded = Convert.ToInt32(precise);
Which will use Math.Round(x, 0); to round and cast for you. It looks neater but is slightly less clear IMO.
//var decimalVar is your variable name