To get wall-to-wheels most people have some sort of dedicated meter on the line that feeds their home EVSE. Obviously, this won't track any electricity used when charging away from home. There are a number of solutions from a refurb utility meters (buy a regular meter socket and the meter online - meter is around $35, socket about the same) - EKM Metering
also has utility grade meters at a reasonable cost with remote monitoring features.
Failing that - the dash/center console readouts are generally slightly higher than what the wall-to-wheel measurement and dosn't include charging losses. L1 charging is less efficient than L2 charging. L1 is generally around high 70% to low 80% efficient, while L2 charging is mid-high 80% efficient. The center console tends to read 0.1 mi/kWh higher than the dash - they can be reset individually and many people reset one (typically the dash) after each charge to watch efficiency.
To calculate cost to charge, simply take your incremental cost of electrcity (which can be different than your average cost shown on your bill if your plan is not a flat-rate plan) and multiply by your estimated wall-to-wheels efficiency and miles driven. Most people typically get from 3.0-4.0 mi/kWh from the wall. So 100 miles will use between 25-33 kWh.
Looks like your rate is less than $0.09/kWh - say you drive 1,000 miles/month at 3.3 mi/kWh will cost you about $27/month or less than 3c/mile!
Your mileage may vary!