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	$71.49	3.670%	$74.1137	$74.11	$74.10	$74.10
Purchase #2	$15.87	9.187%	$17.328	$17.33	$17.35	$17.30
Purchase #3	$97.90	3.428%	$101.256	$101.26	$101.25	$101.30
Purchase #4	$247.53	11.122%	$275.0603	$275.06	$275.05	$275.10
Purchase #5	$71.85	9.102%	$78.3898	$78.39	$78.40	$78.40
Purchase #6	$105.59	5.714%	$111.6234	$111.62	$111.60	$111.60
Purchase #7	$14.85	4.300%	$15.4886	$15.49	$15.50	$15.50
7 purchase totals =	$625.08		$673.2598	$673.26	$673.25	$673.30