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	$193.71	3.692%	$200.8618	$200.86	$200.85	$200.90
Purchase #2	$161.50	8.781%	$175.6813	$175.68	$175.70	$175.70
Purchase #3	$148.34	9.599%	$162.5792	$162.58	$162.60	$162.60
Purchase #4	$117.52	9.375%	$128.5375	$128.54	$128.55	$128.50
Purchase #5	$171.75	11.348%	$191.2402	$191.24	$191.25	$191.20
Purchase #6	$73.79	12.663%	$83.134	$83.13	$83.15	$83.10
Purchase #7	$85.55	10.549%	$94.5747	$94.57	$94.55	$94.60
7 purchase totals =	$952.16		$1,036.6087	$1,036.60	$1,036.65	$1,036.60