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	$96.68	3.144%	$99.7196	$99.72	$99.70	$99.70
Purchase #2	$201.44	6.462%	$214.4571	$214.46	$214.45	$214.50
Purchase #3	$81.60	7.762%	$87.9338	$87.93	$87.95	$87.90
Purchase #4	$201.48	11.366%	$224.3802	$224.38	$224.40	$224.40
Purchase #5	$157.54	10.380%	$173.8927	$173.89	$173.90	$173.90
Purchase #6	$111.79	4.465%	$116.7814	$116.78	$116.80	$116.80
Purchase #7	$98.70	6.834%	$105.4452	$105.45	$105.45	$105.40
7 purchase totals =	$949.23		$1,022.6100	$1,022.61	$1,022.65	$1,022.60