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	$199.82	7.288%	$214.3829	$214.38	$214.40	$214.40
Purchase #2	$200.86	11.460%	$223.8786	$223.88	$223.90	$223.90
Purchase #3	$8.83	8.349%	$9.5672	$9.57	$9.55	$9.60
Purchase #4	$101.63	10.195%	$111.9912	$111.99	$112.00	$112.00
Purchase #5	$223.50	4.612%	$233.8078	$233.81	$233.80	$233.80
Purchase #6	$163.70	9.691%	$179.5642	$179.56	$179.55	$179.60
Purchase #7	$186.48	7.591%	$200.6357	$200.64	$200.65	$200.60
7 purchase totals =	$1,084.82		$1,173.8276	$1,173.83	$1,173.85	$1,173.90