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	$92.86	13.498%	$105.3942	$105.39	$105.40	$105.40
Purchase #2	$10.89	11.336%	$12.1245	$12.12	$12.10	$12.10
Purchase #3	$246.32	6.669%	$262.7471	$262.75	$262.75	$262.70
Purchase #4	$120.36	6.184%	$127.8031	$127.80	$127.80	$127.80
Purchase #5	$158.98	11.415%	$177.1276	$177.13	$177.15	$177.10
Purchase #6	$145.65	13.434%	$165.2166	$165.22	$165.20	$165.20
Purchase #7	$94.52	5.339%	$99.5664	$99.57	$99.55	$99.60
7 purchase totals =	$869.58		$949.9795	$949.98	$949.95	$949.90