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	$177.48	4.298%	$185.1081	$185.11	$185.10	$185.10
Purchase #2	$192.62	11.590%	$214.9447	$214.94	$214.95	$214.90
Purchase #3	$212.87	10.637%	$235.513	$235.51	$235.50	$235.50
Purchase #4	$94.98	11.254%	$105.669	$105.67	$105.65	$105.70
Purchase #5	$152.87	9.488%	$167.3743	$167.37	$167.35	$167.40
Purchase #6	$112.49	13.383%	$127.5445	$127.54	$127.55	$127.50
Purchase #7	$135.78	9.426%	$148.5786	$148.58	$148.60	$148.60
7 purchase totals =	$1,079.09		$1,184.7322	$1,184.72	$1,184.70	$1,184.70