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	$84.28	13.466%	$95.6291	$95.63	$95.65	$95.60
Purchase #2	$131.44	10.466%	$145.1965	$145.20	$145.20	$145.20
Purchase #3	$157.39	12.233%	$176.6435	$176.64	$176.65	$176.60
Purchase #4	$90.35	10.428%	$99.7717	$99.77	$99.75	$99.80
Purchase #5	$155.39	9.339%	$169.9019	$169.90	$169.90	$169.90
Purchase #6	$125.64	6.568%	$133.892	$133.89	$133.90	$133.90
Purchase #7	$231.69	9.418%	$253.5106	$253.51	$253.50	$253.50
7 purchase totals =	$976.18		$1,074.5453	$1,074.54	$1,074.55	$1,074.50