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	$90.81	5.369%	$95.6856	$95.69	$95.70	$95.70
Purchase #2	$117.35	8.187%	$126.9574	$126.96	$126.95	$127.00
Purchase #3	$150.85	10.412%	$166.5565	$166.56	$166.55	$166.60
Purchase #4	$187.86	4.588%	$196.479	$196.48	$196.50	$196.50
Purchase #5	$152.55	5.716%	$161.2698	$161.27	$161.25	$161.30
Purchase #6	$190.26	11.733%	$212.5832	$212.58	$212.60	$212.60
Purchase #7	$92.56	8.219%	$100.1675	$100.17	$100.15	$100.20
7 purchase totals =	$982.24		$1,059.6990	$1,059.71	$1,059.70	$1,059.90