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	$76.35	13.864%	$86.9352	$86.94	$86.95	$86.90
Purchase #2	$78.33	13.228%	$88.6915	$88.69	$88.70	$88.70
Purchase #3	$92.88	13.527%	$105.4439	$105.44	$105.45	$105.40
Purchase #4	$228.77	9.203%	$249.8237	$249.82	$249.80	$249.80
Purchase #5	$73.96	4.829%	$77.5315	$77.53	$77.55	$77.50
Purchase #6	$220.25	8.142%	$238.1828	$238.18	$238.20	$238.20
Purchase #7	$235.60	6.786%	$251.5878	$251.59	$251.60	$251.60
7 purchase totals =	$1,006.14		$1,098.1964	$1,098.19	$1,098.25	$1,098.10