All the PDE5 inhibitors can cause acid reflux, because your esophagus and lower esophageal sphincter also use PDE5 to contract, so the inhibitor can affect their ability to work properly. Usually this only happens in those who already have some level of acid reflux.
Snapping the tablets to take a half dose might not work in this case, because you break the film coating which is there to prevent the PDE5 inhibitor from coming in to contact with the esophagus. Both the 5mg daily low dose and the 20mg event dose are available in half doses (2.5mg and 10mg) for the case where they cause side effects, and often the half dose is still enough for the intended effect, but not the side effects.
You don't want to have frequent acid reflux, as it's a potential cause of esophageal cancer.