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	$166.53	4.454%	$173.9472	$173.95	$173.95	$173.90
Purchase #2	$235.47	10.238%	$259.5774	$259.58	$259.60	$259.60
Purchase #3	$152.27	6.670%	$162.4264	$162.43	$162.45	$162.40
Purchase #4	$85.88	11.308%	$95.5913	$95.59	$95.60	$95.60
Purchase #5	$23.47	4.685%	$24.5696	$24.57	$24.55	$24.60
Purchase #6	$100.32	5.773%	$106.1115	$106.11	$106.10	$106.10
Purchase #7	$178.30	8.743%	$193.8888	$193.89	$193.90	$193.90
7 purchase totals =	$942.24		$1,016.1122	$1,016.12	$1,016.15	$1,016.10