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	$225.59	5.241%	$237.4132	$237.41	$237.40	$237.40
Purchase #2	$39.45	3.586%	$40.8647	$40.86	$40.85	$40.90
Purchase #3	$42.88	11.682%	$47.8892	$47.89	$47.90	$47.90
Purchase #4	$119.44	10.116%	$131.5226	$131.52	$131.50	$131.50
Purchase #5	$233.81	13.374%	$265.0797	$265.08	$265.10	$265.10
Purchase #6	$239.26	11.627%	$267.0788	$267.08	$267.10	$267.10
Purchase #7	$45.93	3.389%	$47.4866	$47.49	$47.50	$47.50
7 purchase totals =	$946.36		$1,037.3348	$1,037.33	$1,037.35	$1,037.40