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	$216.95	5.211%	$228.2553	$228.26	$228.25	$228.30
Purchase #2	$227.33	5.388%	$239.5785	$239.58	$239.60	$239.60
Purchase #3	$73.63	5.386%	$77.5957	$77.60	$77.60	$77.60
Purchase #4	$59.39	5.185%	$62.4694	$62.47	$62.45	$62.50
Purchase #5	$243.34	4.327%	$253.8693	$253.87	$253.85	$253.90
Purchase #6	$206.86	7.258%	$221.8739	$221.87	$221.85	$221.90
Purchase #7	$70.40	11.344%	$78.3862	$78.39	$78.40	$78.40
7 purchase totals =	$1,097.90		$1,162.0283	$1,162.04	$1,162.00	$1,162.20