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	$173.38	13.315%	$196.4655	$196.47	$196.45	$196.50
Purchase #2	$75.64	9.438%	$82.7789	$82.78	$82.80	$82.80
Purchase #3	$132.28	8.456%	$143.4656	$143.47	$143.45	$143.50
Purchase #4	$136.44	6.596%	$145.4396	$145.44	$145.45	$145.40
Purchase #5	$99.41	4.665%	$104.0475	$104.05	$104.05	$104.00
Purchase #6	$170.26	12.856%	$192.1486	$192.15	$192.15	$192.10
Purchase #7	$144.48	3.143%	$149.021	$149.02	$149.00	$149.00
7 purchase totals =	$931.89		$1,013.3667	$1,013.38	$1,013.35	$1,013.30