Money is used in Philip Dick's "Ubik" to show who is not in control. "Ubik"'s very complex plot, however, doesn't reveal who actually is in control. The issue of control with money first shows up when Joe Chip tried to open his door, which demanded a nickel, and threatened to sue him when he started to unscrew it. Opening his fridge and getting something out cost money, as did running water in the bathroom. Since Joe lacked money, he lacked power even over his own apartment. However, it isn't clear whether the appliances or someone beyond were in control.
Next money is significant when Runciter's profile showed up on his anti-psis' coins after the bomb blast. Everything that doesn't have Runciter's manifestation on it was rapidly "reverting" to an older version of itself. The anti-psis didn't know why Runciter was showing up on their coins and matchbooks, since his corpse was in Des Moines and he hadn't been on these items any time in the past. Once again, this shows that the anti-psis weren't in control, but hints that Runciter might have been.
Things seem to be explained when Runciter reveals that he is the only one to have survived the bomb blast and that the others are in half-life. In the half-life Jory seems to be in control, shown by his reverting money to older versions. But everything is shaken up at the end when Joe's profile shows up on Runciter's coin in what is presumed to be real life. Now it is clear that none of these characters is in control. Runciter showed up on Joe's money, but now Joe is showing up on Runciter's money, a conundrum of control. Perhaps Ubik is in control, since it makes Godlike references to itself, but the book ends there, making clear only that it is indeterminate who is in control of what.