I FOUND IT! 3420 is the Perception you want for your MIN/BTN retainers!

[Roth_Trailfinder]

Update for battle retainers:
570 is giving 15 items on level 88 (Ophiotaurus Hide/Berkanan Sap) and 12 on level 89 (Dynamis Crystal). I'm going to guess that 580 will be the goal to get 15 on the Dynamis Crystal.

571 gets 12 of the level 89 items.
574 gets 15 of the level 89 items.

580 is not necessary. Unfortunately I did not have gear to try to narrow the 15 items/venture for level 89 items further.