Fix ceil implementation in NativeFloat64

src/numbers/fixed.rs

@@ -70,9 +70,10 @@ impl Number for Fixed {
 	fn ceil_mut(&mut self, dps: usize) {
 		// Only do something if truncating
 		if dps < get_dps() {
-			self.0 += IBig::one();
+			self.0 -= IBig::one();
 			let factor = IBig::from(10).pow(get_dps() - dps);
 			self.0 /= &factor;
+			self.0 += IBig::one();
 			self.0 *= factor;
 		}
 	}