improved comments and made NowMs round properly

cmix/localTime.go

+////////////////////////////////////////////////////////////////////////////////
+// Copyright © 2022 xx foundation                                             //
+//                                                                            //
+// Use of this source code is governed by a license that can be found in the  //
+// LICENSE file.                                                              //
+////////////////////////////////////////////////////////////////////////////////
+
 package cmix
 
 import "time"
 
+// describes a local time object which gets time
+// from the local clock in milliseconds
 type localTime struct{}
 
 func (localTime) NowMs() int64 {
 	t := time.Now()
-	return t.UnixNano() / int64(time.Millisecond)
+	return (t.UnixNano() + int64(time.Millisecond)/2) / int64(time.Millisecond)
 }