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	$91.70	13.716%	$104.2776	$104.28	$104.30	$104.30
Purchase #2	$94.41	11.201%	$104.9849	$104.98	$105.00	$105.00
Purchase #3	$125.85	6.160%	$133.6024	$133.60	$133.60	$133.60
Purchase #4	$5.56	3.682%	$5.7647	$5.76	$5.75	$5.80
Purchase #5	$90.56	11.636%	$101.0976	$101.10	$101.10	$101.10
Purchase #6	$108.82	3.435%	$112.558	$112.56	$112.55	$112.60
Purchase #7	$150.43	4.501%	$157.2009	$157.20	$157.20	$157.20
7 purchase totals =	$667.33		$719.4861	$719.48	$719.50	$719.60