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	$247.50	5.613%	$261.3922	$261.39	$261.40	$261.40
Purchase #2	$37.44	5.758%	$39.5958	$39.60	$39.60	$39.60
Purchase #3	$183.83	13.359%	$208.3878	$208.39	$208.40	$208.40
Purchase #4	$101.68	10.873%	$112.7357	$112.74	$112.75	$112.70
Purchase #5	$147.83	11.305%	$164.5422	$164.54	$164.55	$164.50
Purchase #6	$155.36	3.193%	$160.3206	$160.32	$160.30	$160.30
Purchase #7	$101.83	9.590%	$111.5955	$111.60	$111.60	$111.60
7 purchase totals =	$975.47		$1,058.5698	$1,058.58	$1,058.60	$1,058.50