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	$104.32	8.810%	$113.5106	$113.51	$113.50	$113.50
Purchase #2	$9.49	11.558%	$10.5869	$10.59	$10.60	$10.60
Purchase #3	$148.94	5.849%	$157.6515	$157.65	$157.65	$157.70
Purchase #4	$80.68	11.256%	$89.7613	$89.76	$89.75	$89.80
Purchase #5	$250.74	5.151%	$263.6556	$263.66	$263.65	$263.70
Purchase #6	$101.27	3.746%	$105.0636	$105.06	$105.05	$105.10
Purchase #7	$154.31	8.544%	$167.4942	$167.49	$167.50	$167.50
7 purchase totals =	$849.75		$907.7237	$907.72	$907.70	$907.90