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	$43.68	9.542%	$47.8479	$47.85	$47.85	$47.80
Purchase #2	$153.66	4.849%	$161.111	$161.11	$161.10	$161.10
Purchase #3	$102.78	10.749%	$113.8278	$113.83	$113.85	$113.80
Purchase #4	$5.94	10.139%	$6.5423	$6.54	$6.55	$6.50
Purchase #5	$50.69	4.565%	$53.004	$53.00	$53.00	$53.00
Purchase #6	$126.94	3.682%	$131.6139	$131.61	$131.60	$131.60
Purchase #7	$195.64	10.269%	$215.7303	$215.73	$215.75	$215.70
7 purchase totals =	$679.33		$729.6772	$729.67	$729.70	$729.50