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	$198.60	3.496%	$205.5431	$205.54	$205.55	$205.50
Purchase #2	$88.25	4.687%	$92.3863	$92.39	$92.40	$92.40
Purchase #3	$221.69	11.527%	$247.2442	$247.24	$247.25	$247.20
Purchase #4	$80.80	4.409%	$84.3625	$84.36	$84.35	$84.40
Purchase #5	$152.69	13.149%	$172.7672	$172.77	$172.75	$172.80
Purchase #6	$214.38	13.113%	$242.4916	$242.49	$242.50	$242.50
Purchase #7	$73.93	6.129%	$78.4612	$78.46	$78.45	$78.50
7 purchase totals =	$1,030.34		$1,123.2561	$1,123.25	$1,123.25	$1,123.30