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	$164.38	9.404%	$179.8383	$179.84	$179.85	$179.80
Purchase #2	$197.47	9.397%	$216.0263	$216.03	$216.05	$216.00
Purchase #3	$116.92	9.202%	$127.679	$127.68	$127.70	$127.70
Purchase #4	$106.89	9.519%	$117.0649	$117.06	$117.05	$117.10
Purchase #5	$105.78	13.346%	$119.8974	$119.90	$119.90	$119.90
Purchase #6	$232.83	4.612%	$243.5681	$243.57	$243.55	$243.60
Purchase #7	$71.44	10.207%	$78.7319	$78.73	$78.75	$78.70
7 purchase totals =	$995.71		$1,082.8059	$1,082.81	$1,082.85	$1,082.80