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	$229.54	9.217%	$250.6967	$250.70	$250.70	$250.70
Purchase #2	$237.51	12.214%	$266.5195	$266.52	$266.50	$266.50
Purchase #3	$112.79	12.635%	$127.041	$127.04	$127.05	$127.00
Purchase #4	$235.85	5.478%	$248.7699	$248.77	$248.75	$248.80
Purchase #5	$17.98	6.465%	$19.1424	$19.14	$19.15	$19.10
Purchase #6	$146.28	3.682%	$151.666	$151.67	$151.65	$151.70
Purchase #7	$95.82	4.769%	$100.3897	$100.39	$100.40	$100.40
7 purchase totals =	$1,075.77		$1,164.2252	$1,164.23	$1,164.20	$1,164.20