You’ll need to purchase a specific bundle if you want to support a specific organization. Wargaming has also posted the dates and times that each bundle will be available.
[Source: Military Appreciation 2015]
World of Tanks and World of Warplanes developer Wargaming is celebrating National Military Appreciation Month by giving a portion of its cash shop proceeds to several veteran organizations. Each week in May, 25 percent of the take from “dedicated in-game currency support packages” will be donated to one of the following organizations: AMVETS, Wounded Warriors Canada, the National Armor and Cavalry Heritage Foundation, and Operation Supply Drop.