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	$164.98	9.849%	$181.2289	$181.23	$181.25	$181.20
Purchase #2	$72.34	11.250%	$80.4783	$80.48	$80.50	$80.50
Purchase #3	$58.83	6.612%	$62.7198	$62.72	$62.70	$62.70
Purchase #4	$169.96	8.791%	$184.9012	$184.90	$184.90	$184.90
Purchase #5	$213.54	13.861%	$243.1388	$243.14	$243.15	$243.10
Purchase #6	$131.78	8.356%	$142.7915	$142.79	$142.80	$142.80
Purchase #7	$61.64	8.325%	$66.7715	$66.77	$66.75	$66.80
7 purchase totals =	$873.07		$962.0300	$962.03	$962.05	$962.00