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	$58.87	4.395%	$61.4573	$61.46	$61.45	$61.50
Purchase #2	$7.94	11.169%	$8.8268	$8.83	$8.85	$8.80
Purchase #3	$130.87	7.275%	$140.3908	$140.39	$140.40	$140.40
Purchase #4	$141.41	7.716%	$152.3212	$152.32	$152.30	$152.30
Purchase #5	$198.78	4.775%	$208.2717	$208.27	$208.25	$208.30
Purchase #6	$228.83	4.365%	$238.8184	$238.82	$238.80	$238.80
Purchase #7	$222.52	7.827%	$239.9366	$239.94	$239.95	$239.90
7 purchase totals =	$989.22		$1,050.0228	$1,050.03	$1,050.00	$1,050.00