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	$190.42	3.172%	$196.4601	$196.46	$196.45	$196.50
Purchase #2	$229.78	13.221%	$260.1592	$260.16	$260.15	$260.20
Purchase #3	$67.91	7.646%	$73.1024	$73.10	$73.10	$73.10
Purchase #4	$136.33	11.244%	$151.6589	$151.66	$151.65	$151.70
Purchase #5	$116.73	8.691%	$126.875	$126.88	$126.90	$126.90
Purchase #6	$79.35	6.372%	$84.4062	$84.41	$84.40	$84.40
Purchase #7	$138.27	9.375%	$151.2328	$151.23	$151.25	$151.20
7 purchase totals =	$958.79		$1,043.8946	$1,043.90	$1,043.90	$1,044.00