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	$50.56	4.623%	$52.8974	$52.90	$52.90	$52.90
Purchase #2	$199.56	7.698%	$214.9221	$214.92	$214.90	$214.90
Purchase #3	$47.75	5.758%	$50.4994	$50.50	$50.50	$50.50
Purchase #4	$159.33	3.102%	$164.2724	$164.27	$164.25	$164.30
Purchase #5	$109.48	6.508%	$116.605	$116.61	$116.60	$116.60
Purchase #6	$183.88	8.271%	$199.0887	$199.09	$199.10	$199.10
Purchase #7	$186.90	13.731%	$212.5632	$212.56	$212.55	$212.60
7 purchase totals =	$937.46		$1,010.8482	$1,010.85	$1,010.80	$1,010.90