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	$61.47	3.482%	$63.6104	$63.61	$63.60	$63.60
Purchase #2	$104.35	7.301%	$111.9686	$111.97	$111.95	$112.00
Purchase #3	$138.39	4.676%	$144.8611	$144.86	$144.85	$144.90
Purchase #4	$53.46	5.454%	$56.3757	$56.38	$56.40	$56.40
Purchase #5	$51.67	4.835%	$54.1682	$54.17	$54.15	$54.20
Purchase #6	$101.94	5.349%	$107.3928	$107.39	$107.40	$107.40
Purchase #7	$137.46	13.721%	$156.3209	$156.32	$156.30	$156.30
7 purchase totals =	$648.74		$694.6977	$694.70	$694.65	$694.80