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	$195.32	4.810%	$204.7149	$204.71	$204.70	$204.70
Purchase #2	$99.74	5.724%	$105.4491	$105.45	$105.45	$105.40
Purchase #3	$148.80	13.278%	$168.5577	$168.56	$168.55	$168.60
Purchase #4	$81.52	6.258%	$86.6215	$86.62	$86.60	$86.60
Purchase #5	$145.72	7.819%	$157.1138	$157.11	$157.10	$157.10
Purchase #6	$218.43	4.632%	$228.5477	$228.55	$228.55	$228.50
Purchase #7	$62.82	9.307%	$68.6667	$68.67	$68.65	$68.70
7 purchase totals =	$952.35		$1,019.6714	$1,019.67	$1,019.60	$1,019.60