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	$174.95	3.533%	$181.131	$181.13	$181.15	$181.10
Purchase #2	$59.82	9.704%	$65.6249	$65.62	$65.60	$65.60
Purchase #3	$243.83	6.215%	$258.984	$258.98	$259.00	$259.00
Purchase #4	$168.75	5.529%	$178.0802	$178.08	$178.10	$178.10
Purchase #5	$150.40	6.756%	$160.561	$160.56	$160.55	$160.60
Purchase #6	$94.54	10.280%	$104.2587	$104.26	$104.25	$104.30
Purchase #7	$87.98	8.353%	$95.329	$95.33	$95.35	$95.30
7 purchase totals =	$980.27		$1,043.9688	$1,043.96	$1,044.00	$1,044.00