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	$103.62	10.731%	$114.7395	$114.74	$114.75	$114.70
Purchase #2	$184.71	7.244%	$198.0904	$198.09	$198.10	$198.10
Purchase #3	$77.53	4.198%	$80.7847	$80.78	$80.80	$80.80
Purchase #4	$114.25	3.743%	$118.5264	$118.53	$118.55	$118.50
Purchase #5	$89.89	12.102%	$100.7685	$100.77	$100.75	$100.80
Purchase #6	$133.75	12.517%	$150.4915	$150.49	$150.50	$150.50
Purchase #7	$38.83	11.792%	$43.4088	$43.41	$43.40	$43.40
7 purchase totals =	$742.58		$806.8098	$806.81	$806.85	$806.80