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	$98.92	5.193%	$104.0569	$104.06	$104.05	$104.10
Purchase #2	$149.33	6.840%	$159.5442	$159.54	$159.55	$159.50
Purchase #3	$179.66	8.117%	$194.243	$194.24	$194.25	$194.20
Purchase #4	$13.65	3.823%	$14.1718	$14.17	$14.15	$14.20
Purchase #5	$248.79	9.499%	$272.4226	$272.42	$272.40	$272.40
Purchase #6	$117.43	8.868%	$127.8437	$127.84	$127.85	$127.80
Purchase #7	$177.85	10.287%	$196.1454	$196.15	$196.15	$196.10
7 purchase totals =	$985.63		$1,068.4276	$1,068.42	$1,068.40	$1,068.30