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	$176.43	11.386%	$196.5183	$196.52	$196.50	$196.50
Purchase #2	$212.41	13.698%	$241.5059	$241.51	$241.50	$241.50
Purchase #3	$94.89	13.716%	$107.9051	$107.91	$107.90	$107.90
Purchase #4	$39.76	10.545%	$43.9527	$43.95	$43.95	$44.00
Purchase #5	$205.39	6.232%	$218.1899	$218.19	$218.20	$218.20
Purchase #6	$220.63	9.287%	$241.1199	$241.12	$241.10	$241.10
Purchase #7	$132.66	3.392%	$137.1598	$137.16	$137.15	$137.20
7 purchase totals =	$1,082.17		$1,186.3516	$1,186.36	$1,186.30	$1,186.40