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	$175.70	11.586%	$196.0566	$196.06	$196.05	$196.10
Purchase #2	$242.96	13.331%	$275.349	$275.35	$275.35	$275.30
Purchase #3	$160.38	3.379%	$165.7992	$165.80	$165.80	$165.80
Purchase #4	$210.91	13.170%	$238.6868	$238.69	$238.70	$238.70
Purchase #5	$27.78	3.646%	$28.7929	$28.79	$28.80	$28.80
Purchase #6	$143.36	5.385%	$151.0799	$151.08	$151.10	$151.10
Purchase #7	$94.26	11.568%	$105.164	$105.16	$105.15	$105.20
7 purchase totals =	$1,055.35		$1,160.9284	$1,160.93	$1,160.95	$1,161.00