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	$94.94	9.509%	$103.9678	$103.97	$103.95	$104.00
Purchase #2	$211.88	13.320%	$240.1024	$240.10	$240.10	$240.10
Purchase #3	$63.29	13.156%	$71.6164	$71.62	$71.60	$71.60
Purchase #4	$87.44	11.224%	$97.2543	$97.25	$97.25	$97.30
Purchase #5	$165.32	3.574%	$171.2285	$171.23	$171.25	$171.20
Purchase #6	$103.39	12.300%	$116.107	$116.11	$116.10	$116.10
Purchase #7	$211.75	3.259%	$218.6509	$218.65	$218.65	$218.70
7 purchase totals =	$938.01		$1,018.9273	$1,018.93	$1,018.90	$1,019.00