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	$191.78	11.130%	$213.1251	$213.13	$213.15	$213.10
Purchase #2	$90.73	5.277%	$95.5178	$95.52	$95.50	$95.50
Purchase #3	$149.71	7.760%	$161.3275	$161.33	$161.35	$161.30
Purchase #4	$81.35	10.759%	$90.1024	$90.10	$90.10	$90.10
Purchase #5	$133.79	11.275%	$148.8748	$148.87	$148.85	$148.90
Purchase #6	$165.89	5.789%	$175.4934	$175.49	$175.50	$175.50
Purchase #7	$146.71	8.689%	$159.4576	$159.46	$159.45	$159.50
7 purchase totals =	$959.96		$1,043.8986	$1,043.90	$1,043.90	$1,043.90