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	$60.60	8.687%	$65.8643	$65.86	$65.85	$65.90
Purchase #2	$75.82	3.701%	$78.6261	$78.63	$78.65	$78.60
Purchase #3	$63.33	4.780%	$66.3572	$66.36	$66.35	$66.40
Purchase #4	$232.33	8.302%	$251.618	$251.62	$251.60	$251.60
Purchase #5	$53.47	4.452%	$55.8505	$55.85	$55.85	$55.90
Purchase #6	$105.36	5.655%	$111.3181	$111.32	$111.30	$111.30
Purchase #7	$117.37	7.615%	$126.3077	$126.31	$126.30	$126.30
7 purchase totals =	$708.28		$755.9419	$755.95	$755.90	$756.00