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	$173.68	13.174%	$196.5606	$196.56	$196.55	$196.60
Purchase #2	$6.90	8.352%	$7.4763	$7.48	$7.50	$7.50
Purchase #3	$143.58	3.438%	$148.5163	$148.52	$148.50	$148.50
Purchase #4	$170.78	3.445%	$176.6634	$176.66	$176.65	$176.70
Purchase #5	$150.96	5.487%	$159.2432	$159.24	$159.25	$159.20
Purchase #6	$64.25	13.554%	$72.9584	$72.96	$72.95	$73.00
Purchase #7	$103.62	7.247%	$111.1293	$111.13	$111.15	$111.10
7 purchase totals =	$813.77		$872.5475	$872.55	$872.55	$872.60