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	$119.81	4.659%	$125.3919	$125.39	$125.40	$125.40
Purchase #2	$165.47	4.129%	$172.3023	$172.30	$172.30	$172.30
Purchase #3	$70.85	10.237%	$78.1029	$78.10	$78.10	$78.10
Purchase #4	$12.58	12.112%	$14.1037	$14.10	$14.10	$14.10
Purchase #5	$54.65	12.482%	$61.4714	$61.47	$61.45	$61.50
Purchase #6	$161.72	3.771%	$167.8185	$167.82	$167.80	$167.80
Purchase #7	$60.26	10.351%	$66.4975	$66.50	$66.50	$66.50
7 purchase totals =	$645.34		$685.6882	$685.68	$685.65	$685.70