The ornamental design for a dispenser tower, as shown and described.
FIG. 1 is a perspective view of a dispenser tower showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a bottom plan view thereof; and,
FIG. 6 is a right end elevational view thereof, with a left end elevational view being a mirror image thereof.
The parts shown in broken lines in FIGS. 1-6 form no part of the claimed design.
The breakaway lines in the drawings indicate no specific length.