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	$206.73	4.737%	$216.5228	$216.52	$216.50	$216.50
Purchase #2	$18.50	6.745%	$19.7478	$19.75	$19.75	$19.70
Purchase #3	$180.30	5.773%	$190.7087	$190.71	$190.70	$190.70
Purchase #4	$78.96	9.634%	$86.567	$86.57	$86.55	$86.60
Purchase #5	$185.60	4.453%	$193.8648	$193.86	$193.85	$193.90
Purchase #6	$41.38	3.784%	$42.9458	$42.95	$42.95	$42.90
Purchase #7	$9.94	4.611%	$10.3983	$10.40	$10.40	$10.40
7 purchase totals =	$721.41		$760.7552	$760.76	$760.70	$760.70