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	$106.27	8.448%	$115.2477	$115.25	$115.25	$115.20
Purchase #2	$69.59	4.572%	$72.7717	$72.77	$72.75	$72.80
Purchase #3	$190.38	4.755%	$199.4326	$199.43	$199.45	$199.40
Purchase #4	$160.56	11.754%	$179.4322	$179.43	$179.45	$179.40
Purchase #5	$172.87	8.124%	$186.914	$186.91	$186.90	$186.90
Purchase #6	$158.95	4.218%	$165.6545	$165.65	$165.65	$165.70
Purchase #7	$186.52	11.850%	$208.6226	$208.62	$208.60	$208.60
7 purchase totals =	$1,045.14		$1,128.0753	$1,128.06	$1,128.05	$1,128.00