The ornamental design for a tray for packagingbox, as shown and described.
FIG. 1 is a front perspective view of a tray for packaging box showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left-side view thereof;
FIG. 5 is a right-side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is another front perspective view thereof; and,
FIG. 9 is another front perspective view thereof, in which a packaging box in broken lines is shown in an exploded view to illustrate an example environment.
The broken lines illustrating portions of the tray for packaging box are for environmental purposes only and form no part of the claimed design.