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	$250.60	4.719%	$262.4258	$262.43	$262.45	$262.40
Purchase #2	$10.77	7.679%	$11.597	$11.60	$11.60	$11.60
Purchase #3	$173.36	4.757%	$181.6067	$181.61	$181.60	$181.60
Purchase #4	$155.89	10.662%	$172.511	$172.51	$172.50	$172.50
Purchase #5	$85.35	10.491%	$94.3041	$94.30	$94.30	$94.30
Purchase #6	$193.91	12.103%	$217.3789	$217.38	$217.40	$217.40
Purchase #7	$56.79	6.742%	$60.6188	$60.62	$60.60	$60.60
7 purchase totals =	$926.67		$1,000.4423	$1,000.45	$1,000.45	$1,000.40