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	$196.93	7.511%	$211.7214	$211.72	$211.70	$211.70
Purchase #2	$227.48	10.597%	$251.5861	$251.59	$251.60	$251.60
Purchase #3	$233.49	12.629%	$262.9775	$262.98	$263.00	$263.00
Purchase #4	$166.83	8.769%	$181.4593	$181.46	$181.45	$181.50
Purchase #5	$73.82	7.822%	$79.5942	$79.59	$79.60	$79.60
Purchase #6	$81.51	5.137%	$85.6972	$85.70	$85.70	$85.70
Purchase #7	$105.85	13.229%	$119.8529	$119.85	$119.85	$119.90
7 purchase totals =	$1,085.91		$1,192.8886	$1,192.89	$1,192.90	$1,193.00