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	$208.38	9.172%	$227.4926	$227.49	$227.50	$227.50
Purchase #2	$92.72	5.807%	$98.1043	$98.10	$98.10	$98.10
Purchase #3	$125.47	7.548%	$134.9405	$134.94	$134.95	$134.90
Purchase #4	$243.37	8.210%	$263.3507	$263.35	$263.35	$263.40
Purchase #5	$54.99	8.136%	$59.464	$59.46	$59.45	$59.50
Purchase #6	$43.66	6.834%	$46.6437	$46.64	$46.65	$46.60
Purchase #7	$183.85	12.240%	$206.3532	$206.35	$206.35	$206.40
7 purchase totals =	$952.44		$1,036.3490	$1,036.33	$1,036.35	$1,036.40