Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$126.92	10.758%	$140.5741	$140.57	$140.55	$140.60
Purchase #2	$87.55	10.642%	$96.8671	$96.87	$96.85	$96.90
Purchase #3	$101.38	10.220%	$111.741	$111.74	$111.75	$111.70
Purchase #4	$45.96	6.207%	$48.8127	$48.81	$48.80	$48.80
Purchase #5	$34.52	11.524%	$38.4981	$38.50	$38.50	$38.50
Purchase #6	$37.98	11.218%	$42.2406	$42.24	$42.25	$42.20
Purchase #7	$224.35	5.790%	$237.3399	$237.34	$237.35	$237.30
7 purchase totals =	$658.66		$716.0735	$716.07	$716.05	$716.00