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	$100.46	10.695%	$111.2042	$111.20	$111.20	$111.20
Purchase #2	$23.82	13.552%	$27.0481	$27.05	$27.05	$27.00
Purchase #3	$243.60	8.755%	$264.9272	$264.93	$264.95	$264.90
Purchase #4	$198.77	9.715%	$218.0805	$218.08	$218.10	$218.10
Purchase #5	$42.77	13.324%	$48.4687	$48.47	$48.45	$48.50
Purchase #6	$153.76	9.268%	$168.0105	$168.01	$168.00	$168.00
Purchase #7	$172.65	13.436%	$195.8473	$195.85	$195.85	$195.80
7 purchase totals =	$935.83		$1,033.5865	$1,033.59	$1,033.60	$1,033.50