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	$60.99	11.192%	$67.816	$67.82	$67.80	$67.80
Purchase #2	$89.85	6.734%	$95.9005	$95.90	$95.90	$95.90
Purchase #3	$162.56	7.793%	$175.2283	$175.23	$175.25	$175.20
Purchase #4	$132.66	13.458%	$150.5134	$150.51	$150.50	$150.50
Purchase #5	$241.38	4.175%	$251.4576	$251.46	$251.45	$251.50
Purchase #6	$99.26	4.870%	$104.094	$104.09	$104.10	$104.10
Purchase #7	$173.84	5.519%	$183.4342	$183.43	$183.45	$183.40
7 purchase totals =	$960.54		$1,028.4440	$1,028.44	$1,028.45	$1,028.40