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	$156.25	7.412%	$167.8313	$167.83	$167.85	$167.80
Purchase #2	$34.73	11.665%	$38.7813	$38.78	$38.80	$38.80
Purchase #3	$193.66	12.225%	$217.3349	$217.33	$217.35	$217.30
Purchase #4	$227.51	11.517%	$253.7123	$253.71	$253.70	$253.70
Purchase #5	$54.63	5.235%	$57.4899	$57.49	$57.50	$57.50
Purchase #6	$119.69	4.276%	$124.8079	$124.81	$124.80	$124.80
Purchase #7	$179.87	5.622%	$189.9823	$189.98	$190.00	$190.00
7 purchase totals =	$966.34		$1,049.9399	$1,049.93	$1,050.00	$1,049.90