Something definitely needs to be done to make candidates more honest. A penalty for proven lies seems like an interesting idea that might work. The FDA regulates claims by food and drug companies. The FCC fines television shows for inappropriate content. Perhaps a government regulatory agency could regulate and even fine political candidates for issuing inaccurate information.
No, I don't think fining a candidate for telling lies during a campaign would help much. In the case of Donald Trump, he's so rich that a fine wouldn't matter to him and he'd keep lying. Perhaps candidates should receive a warning, and if they lie enough times then they should serve time in jail.
No, candidates should not be fined for telling lies during a campaign, but the American people should take note of when a politician lies. The best defense against lying politicians is to not let them win an election. When someone lies, the biggest punishment will be for the voters to go with someone else.
During a campaign, there is freedom to build ones trust and readiness for ones ambitious role. If such claim violate other people opinion, then such claim should be investigate to get the fact. So Donald Trump has an open air to raise innovative ideologies to build trust and support for his presidency.