The meter itself is pretty darn accurate (assuming no outages). Most people on the forums have reported between 1-5% diffrence on usage compared to the power company. My best month I was off by 3 kWh. My worst, 50kWh, but that was due to a network issue in the house.
Keep in mind that the price you enter per kWh may not be all that is needed to compare your bill. For accuracy, I would look at kWh reported by Sense vs the power company.
I’m in MA, so no tiered or TOU pricing, but there are about 8 different “per kWh” items on my bill plus flat monthly charges.
For my kWh number, I took the total bill divided by kWh to come up with a blended rate for what the cost is per kWh.
Check out this thread for some examples.