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	$43.37	11.616%	$48.4079	$48.41	$48.40	$48.40
Purchase #2	$219.38	6.795%	$234.2869	$234.29	$234.30	$234.30
Purchase #3	$119.52	6.401%	$127.1705	$127.17	$127.15	$127.20
Purchase #4	$19.36	7.477%	$20.8075	$20.81	$20.80	$20.80
Purchase #5	$243.36	5.172%	$255.9466	$255.95	$255.95	$255.90
Purchase #6	$161.82	6.411%	$172.1943	$172.19	$172.20	$172.20
Purchase #7	$153.67	12.745%	$173.2552	$173.26	$173.25	$173.30
7 purchase totals =	$960.48		$1,032.0689	$1,032.08	$1,032.05	$1,032.10