She wishes the wish of all wishes.
"I wish that my most sparkly diamond daddy will always be my rock."
With that, her penny is not hers anymore. She knows what she must do if she is to do her part to seal this most important of deals. Then, with her possession still clenched in her two fingers between her two hands she opens her blue eyes. With lashes spread wide and the heave of a deep breath, she casts her magical token of hope and dreams with everything she has. Everything. As if her very life depended on it. Pushing it away from her body she lets go to watch it splash, twirl, and sink to a place where it will be kept safe until the time when the transaction should occur. And with the confidence that comes from a deal well-struck with her mother by her side, she leaves to go find her rock.
And though she remembers committing her penny to the fountain only moments ago, she listens when her sparkly diamond daddy tells her he knows where it went and that it will be safe forever.
And with an approving kiss, she believes him.