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	$119.38	10.699%	$132.1525	$132.15	$132.15	$132.20
Purchase #2	$148.98	11.817%	$166.585	$166.59	$166.60	$166.60
Purchase #3	$44.29	13.500%	$50.2692	$50.27	$50.25	$50.30
Purchase #4	$48.62	12.409%	$54.6533	$54.65	$54.65	$54.70
Purchase #5	$209.87	7.451%	$225.5074	$225.51	$225.50	$225.50
Purchase #6	$216.27	11.115%	$240.3084	$240.31	$240.30	$240.30
Purchase #7	$145.31	13.734%	$165.2669	$165.27	$165.25	$165.30
7 purchase totals =	$932.72		$1,034.7427	$1,034.75	$1,034.70	$1,034.90