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	$134.42	12.353%	$151.0249	$151.02	$151.00	$151.00
Purchase #2	$18.32	6.629%	$19.5344	$19.53	$19.55	$19.50
Purchase #3	$80.72	6.217%	$85.7384	$85.74	$85.75	$85.70
Purchase #4	$217.33	12.477%	$244.4463	$244.45	$244.45	$244.40
Purchase #5	$227.53	7.307%	$244.1556	$244.16	$244.15	$244.20
Purchase #6	$198.59	13.748%	$225.8922	$225.89	$225.90	$225.90
Purchase #7	$210.66	6.149%	$223.6135	$223.61	$223.60	$223.60
7 purchase totals =	$1,087.57		$1,194.4053	$1,194.40	$1,194.40	$1,194.30