Math.round() を使用できます:
http://docs.oracle.com/javase/6/docs/api/java/lang/Math.html#round(float)
例:
1:
// It will round the floats in Vector3F and leave the results as floats
Vector3F vect = new Vector3F(2.3f, 1.114124f, 0f);
vect.x = Math.round(vect.x); // 2f
vect.y = Math.round(vect.x); // 1f
vect.z = Math.round(vect.x); // 0f
2:
// It will round the floats in Vector3F and leave the results as ints
Vector3F vect = new Vector3F(2.3f, 1.114124f, 0f);
int x = Math.round(vect.x);
int y = Math.round(vect.x);
int z = Math.round(vect.x);
詳細情報もあります: How to convert float to int with Java