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	$91.51	4.676%	$95.789	$95.79	$95.80	$95.80
Purchase #2	$182.61	7.798%	$196.8499	$196.85	$196.85	$196.80
Purchase #3	$165.99	5.623%	$175.3236	$175.32	$175.30	$175.30
Purchase #4	$172.89	10.219%	$190.5576	$190.56	$190.55	$190.60
Purchase #5	$119.59	13.617%	$135.8746	$135.87	$135.85	$135.90
Purchase #6	$163.40	10.250%	$180.1485	$180.15	$180.15	$180.10
Purchase #7	$161.45	8.724%	$175.5349	$175.53	$175.55	$175.50
7 purchase totals =	$1,057.44		$1,150.0781	$1,150.07	$1,150.05	$1,150.00