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	$209.71	6.563%	$223.4733	$223.47	$223.45	$223.50
Purchase #2	$8.72	7.159%	$9.3443	$9.34	$9.35	$9.30
Purchase #3	$32.79	8.774%	$35.667	$35.67	$35.65	$35.70
Purchase #4	$135.31	11.805%	$151.2833	$151.28	$151.30	$151.30
Purchase #5	$228.46	5.697%	$241.4754	$241.48	$241.50	$241.50
Purchase #6	$246.77	11.486%	$275.114	$275.11	$275.10	$275.10
Purchase #7	$89.31	12.861%	$100.7962	$100.80	$100.80	$100.80
7 purchase totals =	$951.07		$1,037.1535	$1,037.15	$1,037.15	$1,037.20