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	$200.64	9.502%	$219.7048	$219.70	$219.70	$219.70
Purchase #2	$78.72	8.483%	$85.3978	$85.40	$85.40	$85.40
Purchase #3	$166.81	13.340%	$189.0625	$189.06	$189.05	$189.10
Purchase #4	$138.61	4.768%	$145.2189	$145.22	$145.20	$145.20
Purchase #5	$43.66	8.328%	$47.296	$47.30	$47.30	$47.30
Purchase #6	$205.75	6.727%	$219.5908	$219.59	$219.60	$219.60
Purchase #7	$52.27	13.291%	$59.2172	$59.22	$59.20	$59.20
7 purchase totals =	$886.46		$965.4880	$965.49	$965.45	$965.50