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	$215.52	8.594%	$234.0418	$234.04	$234.05	$234.00
Purchase #2	$217.31	5.769%	$229.8466	$229.85	$229.85	$229.80
Purchase #3	$52.81	11.730%	$59.0046	$59.00	$59.00	$59.00
Purchase #4	$187.27	9.367%	$204.8116	$204.81	$204.80	$204.80
Purchase #5	$71.60	8.603%	$77.7597	$77.76	$77.75	$77.80
Purchase #6	$135.38	3.154%	$139.6499	$139.65	$139.65	$139.60
Purchase #7	$97.52	11.665%	$108.8957	$108.90	$108.90	$108.90
7 purchase totals =	$977.41		$1,054.0099	$1,054.01	$1,054.00	$1,053.90