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	$114.28	4.622%	$119.562	$119.56	$119.55	$119.60
Purchase #2	$193.52	10.524%	$213.886	$213.89	$213.90	$213.90
Purchase #3	$179.58	6.234%	$190.775	$190.78	$190.80	$190.80
Purchase #4	$111.43	8.244%	$120.6163	$120.62	$120.60	$120.60
Purchase #5	$214.80	5.794%	$227.2455	$227.25	$227.25	$227.20
Purchase #6	$69.54	3.176%	$71.7486	$71.75	$71.75	$71.70
Purchase #7	$231.74	8.116%	$250.548	$250.55	$250.55	$250.50
7 purchase totals =	$1,114.89		$1,194.3814	$1,194.40	$1,194.40	$1,194.30