Taking out both tied players doesn't work either. We have 4 suspicious people. Let's just tie them all up and then let them all die. I believe it should only be one death per day vote unless a certain rule is in place. (Bomber!) Moreover, this just encourages lazy play. Let's say you've got 4 votes against you. But over the course of the day, you manage to get 3 people to vote with you against someone else. You're cutting deals to save yourself and then voting ends, you're tied, you're dead.
Great, you managed to take someone with you. But you weren't able to convince anyone from the other bandwagon to switch their vote and vote with you. Why? Because they had no incentive to.They weren't in danger. And even if the vote did get tied, you'd still die anyways. Plus, you might be helping them by taking someone valuable with you.
Thinking about the matter and what I would like to purpose is this: If the vote is tied at the end of the day and not resolved, no one is killed but night actions still go one as normal. Now, I realize people might decry this as unfair right away but I think it has merit. We all know the townies weapon is their vote. This was the thing that people declared was unfair about Pale's mafia with RAB always surviving the vote. It took away their power. So, not killing someone in the vote and letting night actions like mafia hits go on, seems to be putting the balance of power to the mafia. But it really isn't. It's just a consequence for not resolving the tie.
As long as the townies work to resolve the tie and get someone voted out, they still keep their power and can use it. Moreover, it keeps them from being lazy and unconcerned about the vote. It also provides advantages to the players in the bandwagons working to fight off elimination. It eliminates the need for luck to determine the final outcome of the vote. I.E. coin toss. Moreover, townies are not punished for voting against someone and being chosen to die with them because the tie wasn't resolved. While the consequence for not resolving a tie isn't as catastrophic as it has been in the past, (the investigator could still make an investigation that night into the tied players), the fact that it slows the townie effort down might be motivation enough to see that a tie gets resolved.
Moreover, strategy is encouraged and rewarded. The mafia could work to make ties to prevent the townies from getting a vote. Townies will have to think about the vote more. Good players could be able to prevent their deaths.
I guess you could say, Mario Kart Mafia is really the prototype of this kind of a tiebreak. That's how the last day was resolved. You may want to consider that game and day to decide whether this is a strategy worth pursuing since that tiebreak pretty much decided the game. But this is the best solution I've been able to come up with after thinking about the matter.