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	$156.50	9.609%	$171.5381	$171.54	$171.55	$171.50
Purchase #2	$11.82	13.165%	$13.3761	$13.38	$13.40	$13.40
Purchase #3	$12.41	5.385%	$13.0783	$13.08	$13.10	$13.10
Purchase #4	$38.76	9.560%	$42.4655	$42.47	$42.45	$42.50
Purchase #5	$18.45	7.625%	$19.8568	$19.86	$19.85	$19.90
Purchase #6	$165.61	13.260%	$187.5699	$187.57	$187.55	$187.60
Purchase #7	$15.67	4.810%	$16.4237	$16.42	$16.40	$16.40
7 purchase totals =	$419.22		$464.3084	$464.32	$464.30	$464.40