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	$86.63	12.710%	$97.6407	$97.64	$97.65	$97.60
Purchase #2	$87.89	13.523%	$99.7754	$99.78	$99.80	$99.80
Purchase #3	$215.89	6.496%	$229.9142	$229.91	$229.90	$229.90
Purchase #4	$93.89	8.746%	$102.1016	$102.10	$102.10	$102.10
Purchase #5	$155.82	6.863%	$166.5139	$166.51	$166.50	$166.50
Purchase #6	$142.89	8.431%	$154.9371	$154.94	$154.95	$154.90
Purchase #7	$249.74	3.866%	$259.3949	$259.39	$259.40	$259.40
7 purchase totals =	$1,032.75		$1,110.2778	$1,110.27	$1,110.30	$1,110.20