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	$53.92	10.671%	$59.6738	$59.67	$59.65	$59.70
Purchase #2	$99.72	8.848%	$108.5432	$108.54	$108.55	$108.50
Purchase #3	$180.99	8.774%	$196.8701	$196.87	$196.85	$196.90
Purchase #4	$192.80	6.786%	$205.8834	$205.88	$205.90	$205.90
Purchase #5	$174.46	6.841%	$186.3948	$186.39	$186.40	$186.40
Purchase #6	$230.48	12.567%	$259.4444	$259.44	$259.45	$259.40
Purchase #7	$44.94	6.542%	$47.88	$47.88	$47.90	$47.90
7 purchase totals =	$977.31		$1,064.6897	$1,064.67	$1,064.70	$1,064.70