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	$114.71	11.121%	$127.4669	$127.47	$127.45	$127.50
Purchase #2	$10.43	11.745%	$11.655	$11.66	$11.65	$11.70
Purchase #3	$28.58	11.771%	$31.9442	$31.94	$31.95	$31.90
Purchase #4	$88.89	4.361%	$92.7665	$92.77	$92.75	$92.80
Purchase #5	$43.69	6.227%	$46.4106	$46.41	$46.40	$46.40
Purchase #6	$62.63	10.524%	$69.2212	$69.22	$69.20	$69.20
Purchase #7	$110.82	4.189%	$115.4622	$115.46	$115.45	$115.50
7 purchase totals =	$459.75		$494.9266	$494.93	$494.85	$495.00