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	$80.42	7.465%	$86.4234	$86.42	$86.40	$86.40
Purchase #2	$16.60	5.257%	$17.4727	$17.47	$17.45	$17.50
Purchase #3	$30.57	9.864%	$33.5854	$33.59	$33.60	$33.60
Purchase #4	$221.52	9.617%	$242.8236	$242.82	$242.80	$242.80
Purchase #5	$249.66	12.216%	$280.1585	$280.16	$280.15	$280.20
Purchase #6	$153.38	7.725%	$165.2286	$165.23	$165.25	$165.20
Purchase #7	$187.43	6.849%	$200.2671	$200.27	$200.25	$200.30
7 purchase totals =	$939.58		$1,025.9593	$1,025.96	$1,025.90	$1,026.00