Finding a rounded coordinate in a rotated view along Element, MST8i SS4, VBA

Dear All,

I'm drawing a square in rotated View and want to create horizontal lines every X-m. But i'am getting a not rounden X-Cooordinate on the Start of Lines.
So I have perhaps to calculate more Distance, because each line must start with a rounded X-Coordinate.
Only Rounding the coordinate moves the point along the other axis. How can this problem be solved if there is a view rotation angle, a point of displacement of the axes.

I'am Using a Method form John Summers with IPrimitiveCommandEvents for Creating a of Square and other Elements.

Thanks for your Ideas.