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	$114.84	10.118%	$126.4595	$126.46	$126.45	$126.50
Purchase #2	$205.94	3.248%	$212.6289	$212.63	$212.65	$212.60
Purchase #3	$116.65	9.632%	$127.8857	$127.89	$127.90	$127.90
Purchase #4	$116.26	8.147%	$125.7317	$125.73	$125.75	$125.70
Purchase #5	$241.25	12.418%	$271.2084	$271.21	$271.20	$271.20
Purchase #6	$82.96	6.148%	$88.0604	$88.06	$88.05	$88.10
Purchase #7	$86.35	10.563%	$95.4712	$95.47	$95.45	$95.50
7 purchase totals =	$964.25		$1,047.4458	$1,047.45	$1,047.45	$1,047.50