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	$97.84	13.825%	$111.3664	$111.37	$111.35	$111.40
Purchase #2	$189.62	3.509%	$196.2738	$196.27	$196.25	$196.30
Purchase #3	$235.90	4.812%	$247.2515	$247.25	$247.25	$247.30
Purchase #4	$62.38	9.729%	$68.449	$68.45	$68.45	$68.40
Purchase #5	$209.25	6.394%	$222.6294	$222.63	$222.65	$222.60
Purchase #6	$139.92	10.496%	$154.606	$154.61	$154.60	$154.60
Purchase #7	$146.67	3.688%	$152.0792	$152.08	$152.10	$152.10
7 purchase totals =	$1,081.58		$1,152.6553	$1,152.66	$1,152.65	$1,152.70