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	$187.88	10.730%	$208.0395	$208.04	$208.05	$208.00
Purchase #2	$108.97	4.257%	$113.6089	$113.61	$113.60	$113.60
Purchase #3	$190.88	9.439%	$208.8972	$208.90	$208.90	$208.90
Purchase #4	$49.78	3.534%	$51.5392	$51.54	$51.55	$51.50
Purchase #5	$231.91	10.225%	$255.6228	$255.62	$255.60	$255.60
Purchase #6	$121.36	10.599%	$134.2229	$134.22	$134.20	$134.20
Purchase #7	$45.93	3.233%	$47.4149	$47.41	$47.40	$47.40
7 purchase totals =	$936.71		$1,019.3454	$1,019.34	$1,019.30	$1,019.20