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	$64.97	11.684%	$72.5611	$72.56	$72.55	$72.60
Purchase #2	$46.65	12.821%	$52.631	$52.63	$52.65	$52.60
Purchase #3	$45.33	8.851%	$49.3422	$49.34	$49.35	$49.30
Purchase #4	$106.50	5.406%	$112.2574	$112.26	$112.25	$112.30
Purchase #5	$68.56	6.298%	$72.8779	$72.88	$72.90	$72.90
Purchase #6	$113.52	5.481%	$119.742	$119.74	$119.75	$119.70
Purchase #7	$178.85	10.209%	$197.1088	$197.11	$197.10	$197.10
7 purchase totals =	$624.38		$676.5204	$676.52	$676.55	$676.50