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	$182.39	7.600%	$196.2516	$196.25	$196.25	$196.30
Purchase #2	$171.97	4.652%	$179.97	$179.97	$179.95	$180.00
Purchase #3	$208.50	7.301%	$223.7226	$223.72	$223.70	$223.70
Purchase #4	$155.41	7.786%	$167.5102	$167.51	$167.50	$167.50
Purchase #5	$111.94	7.809%	$120.6814	$120.68	$120.70	$120.70
Purchase #6	$146.46	4.235%	$152.6626	$152.66	$152.65	$152.70
Purchase #7	$20.83	4.189%	$21.7026	$21.70	$21.70	$21.70
7 purchase totals =	$997.50		$1,062.5010	$1,062.49	$1,062.45	$1,062.60