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	$110.89	7.389%	$119.0837	$119.08	$119.10	$119.10
Purchase #2	$42.59	10.473%	$47.0505	$47.05	$47.05	$47.10
Purchase #3	$101.37	8.180%	$109.6621	$109.66	$109.65	$109.70
Purchase #4	$239.82	6.685%	$255.852	$255.85	$255.85	$255.90
Purchase #5	$42.81	6.667%	$45.6641	$45.66	$45.65	$45.70
Purchase #6	$208.44	9.186%	$227.5873	$227.59	$227.60	$227.60
Purchase #7	$229.95	8.304%	$249.045	$249.05	$249.05	$249.00
7 purchase totals =	$975.87		$1,053.9447	$1,053.94	$1,053.95	$1,054.10