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	$197.59	3.547%	$204.5985	$204.60	$204.60	$204.60
Purchase #2	$59.38	5.659%	$62.7403	$62.74	$62.75	$62.70
Purchase #3	$137.48	11.677%	$153.5335	$153.53	$153.55	$153.50
Purchase #4	$95.76	8.461%	$103.8623	$103.86	$103.85	$103.90
Purchase #5	$26.46	11.852%	$29.596	$29.60	$29.60	$29.60
Purchase #6	$249.88	9.388%	$273.3387	$273.34	$273.35	$273.30
Purchase #7	$205.33	8.242%	$222.2533	$222.25	$222.25	$222.30
7 purchase totals =	$971.88		$1,049.9226	$1,049.92	$1,049.95	$1,049.90