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	$14.41	3.752%	$14.9507	$14.95	$14.95	$15.00
Purchase #2	$48.25	10.453%	$53.2936	$53.29	$53.30	$53.30
Purchase #3	$70.58	11.365%	$78.6014	$78.60	$78.60	$78.60
Purchase #4	$71.73	4.314%	$74.8244	$74.82	$74.80	$74.80
Purchase #5	$166.84	3.148%	$172.0921	$172.09	$172.10	$172.10
Purchase #6	$210.97	10.846%	$233.8518	$233.85	$233.85	$233.90
Purchase #7	$19.79	13.789%	$22.5188	$22.52	$22.50	$22.50
7 purchase totals =	$602.57		$650.1328	$650.12	$650.10	$650.20