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	$199.85	4.212%	$208.2677	$208.27	$208.25	$208.30
Purchase #2	$48.64	4.578%	$50.8667	$50.87	$50.85	$50.90
Purchase #3	$177.80	10.472%	$196.4192	$196.42	$196.40	$196.40
Purchase #4	$149.81	10.584%	$165.6659	$165.67	$165.65	$165.70
Purchase #5	$160.99	7.201%	$172.5829	$172.58	$172.60	$172.60
Purchase #6	$187.61	13.589%	$213.1043	$213.10	$213.10	$213.10
Purchase #7	$178.93	7.171%	$191.7611	$191.76	$191.75	$191.80
7 purchase totals =	$1,103.63		$1,198.6678	$1,198.67	$1,198.60	$1,198.80