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	$205.37	3.348%	$212.2458	$212.25	$212.25	$212.20
Purchase #2	$19.89	6.713%	$21.2252	$21.23	$21.25	$21.20
Purchase #3	$52.65	5.198%	$55.3867	$55.39	$55.40	$55.40
Purchase #4	$61.97	3.699%	$64.2623	$64.26	$64.25	$64.30
Purchase #5	$39.35	7.105%	$42.1458	$42.15	$42.15	$42.10
Purchase #6	$8.76	9.738%	$9.613	$9.61	$9.60	$9.60
Purchase #7	$246.39	6.556%	$262.5433	$262.54	$262.55	$262.50
7 purchase totals =	$634.38		$667.4221	$667.43	$667.45	$667.30