Correct Rounding Error in calculating actual Supercharging costs

It appears the fractional "Used kWh" amount is included by TeslaFi in multiplying by cost per kWh, but Tesla only charges by the whole kWh, meaning a rounding function might be needed.

Real life example:

Supercharger cost (overridden in the properties of the location): $.23 / kWh

Used kWh: 36.2

TeslaFi calculated cost: $8.33

Actual bill from Tesla: 36 kWh @ $.23 = $8.28

Further investigation shows they round to the nearest whole kWh amount.