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	$111.30	5.776%	$117.7287	$117.73	$117.75	$117.70
Purchase #2	$17.69	3.283%	$18.2708	$18.27	$18.25	$18.30
Purchase #3	$221.28	10.733%	$245.03	$245.03	$245.05	$245.00
Purchase #4	$174.58	6.131%	$185.2835	$185.28	$185.30	$185.30
Purchase #5	$218.62	10.350%	$241.2472	$241.25	$241.25	$241.20
Purchase #6	$38.60	13.254%	$43.716	$43.72	$43.70	$43.70
Purchase #7	$244.46	6.559%	$260.4941	$260.49	$260.50	$260.50
7 purchase totals =	$1,026.53		$1,111.7703	$1,111.77	$1,111.80	$1,111.70