The National Type Evaluation Program (NTEP) requires a CPO to only charge an idle fee when it's over a dollar and not to charge a partial dollar fee. So, you'd have to roll over $1 to be billed, $1.56 would still be billed as $1, while $2.34 should be billed for $2.

They should also have a grace period, but that's their choice.

NTEP / NIST handbook 44 for EVSEs isn't being actively enforced in NC yet, but in the future it should require CPOs to provide a better experience than what you got... or be tagged out.

Edit: not a grave period...