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	$105.92	4.840%	$111.0465	$111.05	$111.05	$111.00
Purchase #2	$144.32	7.347%	$154.9232	$154.92	$154.90	$154.90
Purchase #3	$92.90	5.316%	$97.8386	$97.84	$97.85	$97.80
Purchase #4	$139.57	5.812%	$147.6818	$147.68	$147.70	$147.70
Purchase #5	$231.43	3.213%	$238.8658	$238.87	$238.85	$238.90
Purchase #6	$183.61	5.850%	$194.3512	$194.35	$194.35	$194.40
Purchase #7	$34.30	10.195%	$37.7969	$37.80	$37.80	$37.80
7 purchase totals =	$932.05		$982.5040	$982.51	$982.50	$982.50