Although VOR stations follow magnetic north, do VOR's on a chart follow true north?
Compass rosette will be based on the five year epoch magnetic variation model.
Both the signal and the representation on the sectional chart of a VOR will be oriented to magnetic North. There will be some fluctuation caused by magnetic drift. Adjustments will be made for this.
According to the FAA FAQ website...
Why is there a difference between the magnetic variation for the airport and the VOR located at the same airport?
When a navaid is first constructed, the antenna is physically oriented to True North. Then a potentiometer adjustment is made to slave the navaid with Magnetic North. This action matches the isogonic line making it agree with a magnetic compass. Initially these two values are the same, but the magnetic variation of the earth changes at differing rates depending upon location and time.
Navigational aids go into service and remain online 24 hours a day, 365 days a year. The FAA performs periodic maintenance; however, readjustments to match the isogonic value require a total shut down of the equipment, plus recertification and flight check verification. This process begins when a navigational aid is out of tolerance by at least +/-6 degrees. GPS databases use a MAGVAR model to calculate the most up-to-date magnetic variation.