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	$195.34	10.563%	$215.9738	$215.97	$215.95	$216.00
Purchase #2	$107.63	3.838%	$111.7608	$111.76	$111.75	$111.80
Purchase #3	$64.83	3.487%	$67.0906	$67.09	$67.10	$67.10
Purchase #4	$179.93	5.341%	$189.5401	$189.54	$189.55	$189.50
Purchase #5	$137.62	11.398%	$153.3059	$153.31	$153.30	$153.30
Purchase #6	$157.78	5.778%	$166.8965	$166.90	$166.90	$166.90
Purchase #7	$93.94	11.864%	$105.085	$105.09	$105.10	$105.10
7 purchase totals =	$937.07		$1,009.6527	$1,009.66	$1,009.65	$1,009.70