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	$107.59	3.745%	$111.6192	$111.62	$111.60	$111.60
Purchase #2	$18.33	7.628%	$19.7282	$19.73	$19.75	$19.70
Purchase #3	$47.92	9.370%	$52.4101	$52.41	$52.40	$52.40
Purchase #4	$148.77	10.510%	$164.4057	$164.41	$164.40	$164.40
Purchase #5	$246.54	7.175%	$264.2292	$264.23	$264.25	$264.20
Purchase #6	$146.72	9.301%	$160.3664	$160.37	$160.35	$160.40
Purchase #7	$152.75	11.274%	$169.971	$169.97	$169.95	$170.00
7 purchase totals =	$868.62		$942.7298	$942.74	$942.70	$942.70