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	$177.63	9.483%	$194.4747	$194.47	$194.45	$194.50
Purchase #2	$107.42	4.615%	$112.3774	$112.38	$112.40	$112.40
Purchase #3	$53.89	10.645%	$59.6266	$59.63	$59.65	$59.60
Purchase #4	$205.29	7.596%	$220.8838	$220.88	$220.90	$220.90
Purchase #5	$186.66	5.471%	$196.8722	$196.87	$196.85	$196.90
Purchase #6	$77.72	11.324%	$86.521	$86.52	$86.50	$86.50
Purchase #7	$139.29	12.188%	$156.2667	$156.27	$156.25	$156.30
7 purchase totals =	$947.90		$1,027.0224	$1,027.02	$1,027.00	$1,027.10