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	$186.62	11.694%	$208.4433	$208.44	$208.45	$208.40
Purchase #2	$229.51	11.481%	$255.86	$255.86	$255.85	$255.90
Purchase #3	$26.31	9.279%	$28.7513	$28.75	$28.75	$28.80
Purchase #4	$160.49	7.273%	$172.1624	$172.16	$172.15	$172.20
Purchase #5	$228.58	5.839%	$241.9268	$241.93	$241.95	$241.90
Purchase #6	$119.78	3.165%	$123.571	$123.57	$123.55	$123.60
Purchase #7	$95.88	11.693%	$107.0912	$107.09	$107.10	$107.10
7 purchase totals =	$1,047.17		$1,137.8060	$1,137.80	$1,137.80	$1,137.90