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	$218.65	11.249%	$243.2459	$243.25	$243.25	$243.20
Purchase #2	$101.68	9.623%	$111.4647	$111.46	$111.45	$111.50
Purchase #3	$66.42	6.711%	$70.8774	$70.88	$70.90	$70.90
Purchase #4	$157.72	8.835%	$171.6546	$171.65	$171.65	$171.70
Purchase #5	$200.40	12.550%	$225.5502	$225.55	$225.55	$225.60
Purchase #6	$121.27	8.639%	$131.7465	$131.75	$131.75	$131.70
Purchase #7	$97.98	7.772%	$105.595	$105.60	$105.60	$105.60
7 purchase totals =	$964.12		$1,060.1343	$1,060.14	$1,060.15	$1,060.20