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	$187.52	11.434%	$208.961	$208.96	$208.95	$209.00
Purchase #2	$129.37	10.320%	$142.721	$142.72	$142.70	$142.70
Purchase #3	$157.45	8.379%	$170.6427	$170.64	$170.65	$170.60
Purchase #4	$114.45	6.690%	$122.1067	$122.11	$122.10	$122.10
Purchase #5	$90.89	13.472%	$103.1347	$103.13	$103.15	$103.10
Purchase #6	$82.34	10.151%	$90.6983	$90.70	$90.70	$90.70
Purchase #7	$183.83	8.811%	$200.0273	$200.03	$200.05	$200.00
7 purchase totals =	$945.85		$1,038.2917	$1,038.29	$1,038.30	$1,038.20