FIG. 1 is a perspective view of a siding joint cover with locking tabs showing our new design, the broken lines showing siding panels are for illustrative purposes only, and form no part of the claimed design;

FIG. 2 is a perspective view of a first embodiment of the siding joint cover with locking tabs;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a front elevational view thereof;

FIG. 6 is a left side elevational view thereof;

FIG. 7 is a bottom plan view thereof;

FIG. 8 is a top plan view thereof;

FIG. 9 is a perspective view of a second embodiment of a siding joint cover with locking tabs showing our new design, the broken lines showing siding panels are for illustrative purposes only, and form no part of the claimed design;

FIG. 10 is a rear elevational view thereof;

FIG. 11 is a right side elevational view thereof;

FIG. 12 is a front elevational view thereof;

FIG. 13 is a left side elevational view thereof;

FIG. 14 is a bottom plan view thereof; and,

FIG. 15 is a top plan view thereof.