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	$74.26	11.457%	$82.768	$82.77	$82.75	$82.80
Purchase #2	$114.41	10.523%	$126.4494	$126.45	$126.45	$126.40
Purchase #3	$159.56	3.127%	$164.5494	$164.55	$164.55	$164.50
Purchase #4	$246.87	5.504%	$260.4577	$260.46	$260.45	$260.50
Purchase #5	$137.54	5.824%	$145.5503	$145.55	$145.55	$145.60
Purchase #6	$137.66	6.677%	$146.8516	$146.85	$146.85	$146.90
Purchase #7	$152.34	10.338%	$168.0889	$168.09	$168.10	$168.10
7 purchase totals =	$1,022.64		$1,094.7153	$1,094.72	$1,094.70	$1,094.80