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	$121.80	8.746%	$132.4526	$132.45	$132.45	$132.50
Purchase #2	$141.82	6.526%	$151.0752	$151.08	$151.10	$151.10
Purchase #3	$228.48	6.185%	$242.6115	$242.61	$242.60	$242.60
Purchase #4	$117.86	7.868%	$127.1332	$127.13	$127.15	$127.10
Purchase #5	$151.44	7.313%	$162.5148	$162.51	$162.50	$162.50
Purchase #6	$129.69	11.180%	$144.1893	$144.19	$144.20	$144.20
Purchase #7	$200.80	6.595%	$214.0428	$214.04	$214.05	$214.00
7 purchase totals =	$1,091.89		$1,174.0194	$1,174.01	$1,174.05	$1,174.00