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	$140.96	9.865%	$154.8657	$154.87	$154.85	$154.90
Purchase #2	$12.44	9.398%	$13.6091	$13.61	$13.60	$13.60
Purchase #3	$111.99	11.404%	$124.7613	$124.76	$124.75	$124.80
Purchase #4	$145.32	5.617%	$153.4826	$153.48	$153.50	$153.50
Purchase #5	$171.82	5.245%	$180.832	$180.83	$180.85	$180.80
Purchase #6	$44.49	8.636%	$48.3322	$48.33	$48.35	$48.30
Purchase #7	$181.25	8.234%	$196.1741	$196.17	$196.15	$196.20
7 purchase totals =	$808.27		$872.0570	$872.05	$872.05	$872.10