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	$55.83	6.477%	$59.4461	$59.45	$59.45	$59.40
Purchase #2	$66.29	11.363%	$73.8225	$73.82	$73.80	$73.80
Purchase #3	$19.75	9.334%	$21.5935	$21.59	$21.60	$21.60
Purchase #4	$51.60	4.441%	$53.8916	$53.89	$53.90	$53.90
Purchase #5	$144.76	5.709%	$153.0243	$153.02	$153.00	$153.00
Purchase #6	$154.92	7.445%	$166.4538	$166.45	$166.45	$166.50
Purchase #7	$187.50	9.638%	$205.5713	$205.57	$205.55	$205.60
7 purchase totals =	$680.65		$733.8031	$733.79	$733.75	$733.80