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	$69.91	11.491%	$77.9434	$77.94	$77.95	$77.90
Purchase #2	$161.73	7.795%	$174.3369	$174.34	$174.35	$174.30
Purchase #3	$129.43	10.183%	$142.6099	$142.61	$142.60	$142.60
Purchase #4	$19.52	11.299%	$21.7256	$21.73	$21.75	$21.70
Purchase #5	$175.85	6.411%	$187.1237	$187.12	$187.10	$187.10
Purchase #6	$190.83	4.529%	$199.4727	$199.47	$199.45	$199.50
Purchase #7	$225.37	11.742%	$251.8329	$251.83	$251.85	$251.80
7 purchase totals =	$972.64		$1,055.0451	$1,055.04	$1,055.05	$1,054.90