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	$173.93	12.413%	$195.5199	$195.52	$195.50	$195.50
Purchase #2	$137.34	12.651%	$154.7149	$154.71	$154.70	$154.70
Purchase #3	$112.46	12.173%	$126.1498	$126.15	$126.15	$126.10
Purchase #4	$171.48	13.738%	$195.0379	$195.04	$195.05	$195.00
Purchase #5	$74.69	9.824%	$82.0275	$82.03	$82.05	$82.00
Purchase #6	$138.96	13.747%	$158.0628	$158.06	$158.05	$158.10
Purchase #7	$100.66	7.559%	$108.2689	$108.27	$108.25	$108.30
7 purchase totals =	$909.52		$1,019.7817	$1,019.78	$1,019.75	$1,019.70