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	$191.64	7.186%	$205.4113	$205.41	$205.40	$205.40
Purchase #2	$176.42	7.720%	$190.0396	$190.04	$190.05	$190.00
Purchase #3	$201.93	12.482%	$227.1349	$227.13	$227.15	$227.10
Purchase #4	$153.61	7.350%	$164.9003	$164.90	$164.90	$164.90
Purchase #5	$66.89	8.661%	$72.6833	$72.68	$72.70	$72.70
Purchase #6	$179.46	9.414%	$196.3544	$196.35	$196.35	$196.40
Purchase #7	$111.65	9.155%	$121.8716	$121.87	$121.85	$121.90
7 purchase totals =	$1,081.60		$1,178.3954	$1,178.38	$1,178.40	$1,178.40