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	$202.53	4.191%	$211.018	$211.02	$211.00	$211.00
Purchase #2	$144.33	5.242%	$151.8958	$151.90	$151.90	$151.90
Purchase #3	$65.57	11.223%	$72.9289	$72.93	$72.95	$72.90
Purchase #4	$217.61	8.108%	$235.2538	$235.25	$235.25	$235.30
Purchase #5	$134.72	6.227%	$143.109	$143.11	$143.10	$143.10
Purchase #6	$94.31	10.764%	$104.4615	$104.46	$104.45	$104.50
Purchase #7	$109.29	4.724%	$114.4529	$114.45	$114.45	$114.50
7 purchase totals =	$968.36		$1,033.1199	$1,033.12	$1,033.10	$1,033.20