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	$95.61	11.764%	$106.8576	$106.86	$106.85	$106.90
Purchase #2	$207.89	12.423%	$233.7162	$233.72	$233.70	$233.70
Purchase #3	$228.50	5.527%	$241.1292	$241.13	$241.15	$241.10
Purchase #4	$116.56	12.536%	$131.172	$131.17	$131.15	$131.20
Purchase #5	$192.42	5.448%	$202.903	$202.90	$202.90	$202.90
Purchase #6	$162.40	10.835%	$179.996	$180.00	$180.00	$180.00
Purchase #7	$66.52	7.500%	$71.509	$71.51	$71.50	$71.50
7 purchase totals =	$1,069.90		$1,167.2830	$1,167.29	$1,167.25	$1,167.30