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	$216.98	5.748%	$229.452	$229.45	$229.45	$229.50
Purchase #2	$218.76	5.612%	$231.0368	$231.04	$231.05	$231.00
Purchase #3	$138.59	7.118%	$148.4548	$148.45	$148.45	$148.50
Purchase #4	$185.79	5.716%	$196.4098	$196.41	$196.40	$196.40
Purchase #5	$181.88	7.866%	$196.1867	$196.19	$196.20	$196.20
Purchase #6	$41.92	6.287%	$44.5555	$44.56	$44.55	$44.60
Purchase #7	$213.72	8.235%	$231.3198	$231.32	$231.30	$231.30
7 purchase totals =	$1,197.64		$1,277.4154	$1,277.42	$1,277.40	$1,277.50