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	$111.89	12.658%	$126.053	$126.05	$126.05	$126.10
Purchase #2	$71.37	10.719%	$79.0202	$79.02	$79.00	$79.00
Purchase #3	$164.39	5.128%	$172.8199	$172.82	$172.80	$172.80
Purchase #4	$155.43	12.509%	$174.8727	$174.87	$174.85	$174.90
Purchase #5	$37.49	4.689%	$39.2479	$39.25	$39.25	$39.20
Purchase #6	$166.87	11.129%	$185.441	$185.44	$185.45	$185.40
Purchase #7	$205.37	11.838%	$229.6817	$229.68	$229.70	$229.70
7 purchase totals =	$912.81		$1,007.1364	$1,007.13	$1,007.10	$1,007.10