Even over textured surfaces, it's easy to get perfectly straight paint lines every time without the paint running under the tape.

Next run a thin bead of caulk along the edge to be painted and wipe clean with a damp rag.  I recommend using a clear latex caulk, since it is easy to clean up with water and will not show against the color of the surface under the tape.  

This will leave a very small amount of caulk to fill in the edge of the tape and the valleys of the texture, ensuring the paint won't run under the tape.

Paint your second color, and if possible remove the tape while the paint is still wet.  Second coats may be brought up close to this line without ruining your line.  Two coats may be too thick to pull the tape off without peeling the paint.

If the paint has dried, slowly pull the tape back flat; you may need to cut the paint on the tape line with a razor blade to keep the paint from peeling.