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	$85.50	12.553%	$96.2328	$96.23	$96.25	$96.20
Purchase #2	$44.87	8.361%	$48.6216	$48.62	$48.60	$48.60
Purchase #3	$98.81	3.186%	$101.9581	$101.96	$101.95	$102.00
Purchase #4	$147.55	3.172%	$152.2303	$152.23	$152.25	$152.20
Purchase #5	$67.32	9.708%	$73.8554	$73.86	$73.85	$73.90
Purchase #6	$227.49	12.328%	$255.535	$255.54	$255.55	$255.50
Purchase #7	$215.81	9.108%	$235.466	$235.47	$235.45	$235.50
7 purchase totals =	$887.35		$963.8992	$963.91	$963.90	$963.90