Let me explain what coverage you are choosing.
$15,000/$30,000/$5,000 is the minimum limits in your state. Now the 1st (2) numbers are for injuries you cause if found at fault in an accident. So in A case, the MAX your policy would pay is $15,000 (per) person and the MAX it will pay for (2) or more people injured is $30,000. The last number $5,000 is for property damages, which in most cases is an auto/truck, but could also be other property damages like hitting a sign, fence etc.
Now you are in an accident and found at fault. The other car has $8,000 damages and there is a driver/passenger who is injured, goes to the ER and has surgery and the total hospital bill is $40,000. But they came home and also need rehab treatment, thus another $8,000, totaling $48,000 in medical bills.
Your insurance pays them $5,000 for the car damages. They also pay the injured driver $15,000, since that is the max that you bought. $48,000 - $15,000 = $33,000. $8,000 - $5,000 = $3,000. Now since you bought the minimum (legal) limits, then they go after you/sue for the difference of $36,000.
I have always had $100,000/$300,000/$100,000 until I handled auto claims and saw too many times when there was not enough coverage, thus I increased my limits to $250,000/$500,000/$250,000 (plus) a umbrella policy that covers me to 1 million. What surprised me was that by increasing the limits only cost me about $20 more?
So for $100 more, you would get (almost) double in liability, (plus) adding collision/comprehensive to cover (your) own car damages. But like many others have stated, I bet if you got $100,000/$300,000/$50,000 or $100,000 property damages then the cost might be $30.00 or $50.00 more for the increase.
The question is, would you rather pay a couple hundred less, but then take the chance of being sued if not enough?
retired auto adjuster