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	$48.51	7.532%	$52.1638	$52.16	$52.15	$52.20
Purchase #2	$79.59	7.235%	$85.3483	$85.35	$85.35	$85.30
Purchase #3	$105.66	7.193%	$113.2601	$113.26	$113.25	$113.30
Purchase #4	$224.41	11.133%	$249.3936	$249.39	$249.40	$249.40
Purchase #5	$40.59	8.268%	$43.946	$43.95	$43.95	$43.90
Purchase #6	$187.67	4.533%	$196.1771	$196.18	$196.20	$196.20
Purchase #7	$43.34	9.655%	$47.5245	$47.52	$47.50	$47.50
7 purchase totals =	$729.77		$787.8134	$787.81	$787.80	$787.80