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	$202.94	4.337%	$211.7415	$211.74	$211.75	$211.70
Purchase #2	$20.82	9.194%	$22.7342	$22.73	$22.75	$22.70
Purchase #3	$71.80	8.762%	$78.0911	$78.09	$78.10	$78.10
Purchase #4	$20.40	7.325%	$21.8943	$21.89	$21.90	$21.90
Purchase #5	$190.88	4.232%	$198.958	$198.96	$198.95	$199.00
Purchase #6	$174.78	12.432%	$196.5086	$196.51	$196.50	$196.50
Purchase #7	$226.77	12.806%	$255.8102	$255.81	$255.80	$255.80
7 purchase totals =	$908.39		$985.7379	$985.73	$985.75	$985.70