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	$186.61	4.313%	$194.6585	$194.66	$194.65	$194.70
Purchase #2	$75.39	10.757%	$83.4997	$83.50	$83.50	$83.50
Purchase #3	$187.83	13.182%	$212.5898	$212.59	$212.60	$212.60
Purchase #4	$191.34	13.829%	$217.8004	$217.80	$217.80	$217.80
Purchase #5	$19.93	12.494%	$22.4201	$22.42	$22.40	$22.40
Purchase #6	$162.81	13.559%	$184.8854	$184.89	$184.90	$184.90
Purchase #7	$92.91	13.558%	$105.5067	$105.51	$105.50	$105.50
7 purchase totals =	$916.82		$1,021.3606	$1,021.37	$1,021.35	$1,021.40