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	$67.25	3.552%	$69.6387	$69.64	$69.65	$69.60
Purchase #2	$120.55	11.380%	$134.2686	$134.27	$134.25	$134.30
Purchase #3	$101.33	9.771%	$111.231	$111.23	$111.25	$111.20
Purchase #4	$80.65	11.399%	$89.8433	$89.84	$89.85	$89.80
Purchase #5	$223.98	3.238%	$231.2325	$231.23	$231.25	$231.20
Purchase #6	$121.68	4.419%	$127.057	$127.06	$127.05	$127.10
Purchase #7	$241.68	9.837%	$265.4541	$265.45	$265.45	$265.50
7 purchase totals =	$957.12		$1,028.7252	$1,028.72	$1,028.75	$1,028.70