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	$49.86	4.345%	$52.0264	$52.03	$52.05	$52.00
Purchase #2	$173.46	4.225%	$180.7887	$180.79	$180.80	$180.80
Purchase #3	$158.94	4.338%	$165.8348	$165.83	$165.85	$165.80
Purchase #4	$39.43	4.401%	$41.1653	$41.17	$41.15	$41.20
Purchase #5	$242.32	3.795%	$251.516	$251.52	$251.50	$251.50
Purchase #6	$56.83	11.278%	$63.2393	$63.24	$63.25	$63.20
Purchase #7	$234.83	3.348%	$242.6921	$242.69	$242.70	$242.70
7 purchase totals =	$955.67		$997.2626	$997.27	$997.30	$997.20