  We demonstrate that magnetoresistance of creeping charge-density waves in the
quasi-one dimensional conductor {\it o}-TaS$_3$ changes its character from a
negative parabolic at $T\gtrsim 10$ K where it obeys $1/T^2$ law to a weakly
temperature dependent negative nearly linear one at lower temperatures. The
dominant contribution into the negative parabolic magnetoresistance comes from
magnetic field induced splitting of the CDW order parameter. The linear
magnetoresistance arises due to CDW quantum interference similar to the
scenario of negative linear magnetoresistance in single-electron systems.
