The VPS time is usually inherited from the host system, but individual VPS can be set to maintain independent times
From a root prompt on the VM, type the command:
echo 1 > /proc/sys/xen/independent_wallclock
This can be persisted across reboots by changing the /etc/sysctl.conf configuration file and adding:
# Set independent wall clock time
xen.independent_wallclock=1