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	$61.30	3.783%	$63.619	$63.62	$63.60	$63.60
Purchase #2	$164.41	12.298%	$184.6291	$184.63	$184.65	$184.60
Purchase #3	$166.69	5.508%	$175.8713	$175.87	$175.85	$175.90
Purchase #4	$127.46	3.458%	$131.8676	$131.87	$131.85	$131.90
Purchase #5	$92.77	3.168%	$95.709	$95.71	$95.70	$95.70
Purchase #6	$234.26	12.174%	$262.7788	$262.78	$262.80	$262.80
Purchase #7	$30.96	3.474%	$32.0356	$32.04	$32.05	$32.00
7 purchase totals =	$877.85		$946.5104	$946.52	$946.50	$946.50