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	$86.50	6.743%	$92.3327	$92.33	$92.35	$92.30
Purchase #2	$72.25	11.146%	$80.303	$80.30	$80.30	$80.30
Purchase #3	$43.68	6.198%	$46.3873	$46.39	$46.40	$46.40
Purchase #4	$39.79	7.603%	$42.8152	$42.82	$42.80	$42.80
Purchase #5	$131.99	3.364%	$136.4301	$136.43	$136.45	$136.40
Purchase #6	$20.42	8.172%	$22.0887	$22.09	$22.10	$22.10
Purchase #7	$78.53	6.667%	$83.7656	$83.77	$83.75	$83.80
7 purchase totals =	$473.16		$504.1226	$504.13	$504.15	$504.10