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	$56.97	3.702%	$59.079	$59.08	$59.10	$59.10
Purchase #2	$68.50	5.267%	$72.1079	$72.11	$72.10	$72.10
Purchase #3	$194.72	3.688%	$201.9013	$201.90	$201.90	$201.90
Purchase #4	$9.69	4.711%	$10.1465	$10.15	$10.15	$10.10
Purchase #5	$24.89	12.103%	$27.9024	$27.90	$27.90	$27.90
Purchase #6	$228.94	3.240%	$236.3577	$236.36	$236.35	$236.40
Purchase #7	$233.62	9.377%	$255.5265	$255.53	$255.55	$255.50
7 purchase totals =	$817.33		$863.0213	$863.03	$863.05	$863.00