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	$196.65	9.759%	$215.8411	$215.84	$215.85	$215.80
Purchase #2	$189.82	13.560%	$215.5596	$215.56	$215.55	$215.60
Purchase #3	$85.76	4.219%	$89.3782	$89.38	$89.40	$89.40
Purchase #4	$123.43	3.397%	$127.6229	$127.62	$127.60	$127.60
Purchase #5	$150.32	7.467%	$161.5444	$161.54	$161.55	$161.50
Purchase #6	$176.44	6.331%	$187.6104	$187.61	$187.60	$187.60
Purchase #7	$55.53	3.540%	$57.4958	$57.50	$57.50	$57.50
7 purchase totals =	$977.95		$1,055.0524	$1,055.05	$1,055.05	$1,055.00