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	$44.91	3.201%	$46.3476	$46.35	$46.35	$46.30
Purchase #2	$141.33	3.222%	$145.8837	$145.88	$145.90	$145.90
Purchase #3	$94.69	11.488%	$105.568	$105.57	$105.55	$105.60
Purchase #4	$163.89	3.520%	$169.6589	$169.66	$169.65	$169.70
Purchase #5	$247.32	5.867%	$261.8303	$261.83	$261.85	$261.80
Purchase #6	$213.39	4.315%	$222.5978	$222.60	$222.60	$222.60
Purchase #7	$220.25	7.589%	$236.9648	$236.96	$236.95	$237.00
7 purchase totals =	$1,125.78		$1,188.8511	$1,188.85	$1,188.85	$1,188.90