Whether prize-winning strategy in slot machine is so necessary

The question which is more often set by the fans of the advanced slot machines is the following one: is it important, what suitcase (purse, packing) should be chosen during bonus game?
It seems that it is difficult to answer this marvelously simple question! First, it is necessary to clear up the essence of this question. The majority of people wonder, whether Random Numbers Generator defines in advance the bonus sum in slot machine and result of prize-winning game irrespective of the chosen subject?

In other words, I wish to know, as well as any other player, whether slot machine sets in advance - at the very beginning of bonus game - its end result, or it uses Random Numbers Generator for definition of the size of a bonus while we specify what