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	$90.83	4.672%	$95.0736	$95.07	$95.05	$95.10
Purchase #2	$60.61	11.852%	$67.7935	$67.79	$67.80	$67.80
Purchase #3	$245.43	12.127%	$275.1933	$275.19	$275.20	$275.20
Purchase #4	$83.57	8.757%	$90.8882	$90.89	$90.90	$90.90
Purchase #5	$218.85	3.763%	$227.0853	$227.09	$227.10	$227.10
Purchase #6	$148.87	3.355%	$153.8646	$153.86	$153.85	$153.90
Purchase #7	$217.64	4.501%	$227.436	$227.44	$227.45	$227.40
7 purchase totals =	$1,065.80		$1,137.3345	$1,137.33	$1,137.35	$1,137.40