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	$226.76	5.255%	$238.6762	$238.68	$238.70	$238.70
Purchase #2	$139.26	11.484%	$155.2526	$155.25	$155.25	$155.30
Purchase #3	$159.75	3.534%	$165.3956	$165.40	$165.40	$165.40
Purchase #4	$156.56	12.390%	$175.9578	$175.96	$175.95	$176.00
Purchase #5	$55.38	4.536%	$57.892	$57.89	$57.90	$57.90
Purchase #6	$157.29	9.587%	$172.3694	$172.37	$172.35	$172.40
Purchase #7	$72.54	8.823%	$78.9402	$78.94	$78.95	$78.90
7 purchase totals =	$967.54		$1,044.4838	$1,044.49	$1,044.50	$1,044.60