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	$146.79	10.468%	$162.156	$162.16	$162.15	$162.20
Purchase #2	$33.80	8.639%	$36.72	$36.72	$36.70	$36.70
Purchase #3	$100.86	13.602%	$114.579	$114.58	$114.60	$114.60
Purchase #4	$173.88	9.804%	$190.9272	$190.93	$190.95	$190.90
Purchase #5	$83.38	10.612%	$92.2283	$92.23	$92.25	$92.20
Purchase #6	$19.26	11.464%	$21.468	$21.47	$21.45	$21.50
Purchase #7	$73.90	13.406%	$83.807	$83.81	$83.80	$83.80
7 purchase totals =	$631.87		$701.8855	$701.90	$701.90	$701.90