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	$178.31	11.849%	$199.438	$199.44	$199.45	$199.40
Purchase #2	$91.50	6.726%	$97.6543	$97.65	$97.65	$97.70
Purchase #3	$75.72	11.613%	$84.5134	$84.51	$84.50	$84.50
Purchase #4	$135.27	12.481%	$152.153	$152.15	$152.15	$152.20
Purchase #5	$174.38	12.537%	$196.242	$196.24	$196.25	$196.20
Purchase #6	$92.81	6.208%	$98.5716	$98.57	$98.55	$98.60
Purchase #7	$171.59	11.150%	$190.7223	$190.72	$190.70	$190.70
7 purchase totals =	$919.58		$1,019.2946	$1,019.28	$1,019.25	$1,019.30