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	$162.40	10.758%	$179.871	$179.87	$179.85	$179.90
Purchase #2	$168.80	8.613%	$183.3387	$183.34	$183.35	$183.30
Purchase #3	$83.31	13.646%	$94.6785	$94.68	$94.70	$94.70
Purchase #4	$182.62	4.512%	$190.8598	$190.86	$190.85	$190.90
Purchase #5	$104.55	12.495%	$117.6135	$117.61	$117.60	$117.60
Purchase #6	$148.26	3.561%	$153.5395	$153.54	$153.55	$153.50
Purchase #7	$134.46	5.308%	$141.5971	$141.60	$141.60	$141.60
7 purchase totals =	$984.40		$1,061.4981	$1,061.50	$1,061.50	$1,061.50