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	$196.89	9.518%	$215.63	$215.63	$215.65	$215.60
Purchase #2	$249.92	8.141%	$270.266	$270.27	$270.25	$270.30
Purchase #3	$70.71	13.304%	$80.1173	$80.12	$80.10	$80.10
Purchase #4	$45.42	6.540%	$48.3905	$48.39	$48.40	$48.40
Purchase #5	$83.69	4.213%	$87.2159	$87.22	$87.20	$87.20
Purchase #6	$223.83	10.532%	$247.4038	$247.40	$247.40	$247.40
Purchase #7	$111.51	4.837%	$116.9037	$116.90	$116.90	$116.90
7 purchase totals =	$981.97		$1,065.9272	$1,065.93	$1,065.90	$1,065.90