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	$214.90	8.451%	$233.0612	$233.06	$233.05	$233.10
Purchase #2	$115.52	9.327%	$126.2946	$126.29	$126.30	$126.30
Purchase #3	$61.40	3.129%	$63.3212	$63.32	$63.30	$63.30
Purchase #4	$71.71	12.314%	$80.5404	$80.54	$80.55	$80.50
Purchase #5	$78.85	13.123%	$89.1975	$89.20	$89.20	$89.20
Purchase #6	$128.38	9.559%	$140.6518	$140.65	$140.65	$140.70
Purchase #7	$187.47	13.318%	$212.4373	$212.44	$212.45	$212.40
7 purchase totals =	$858.23		$945.5040	$945.50	$945.50	$945.50