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	$176.88	8.296%	$191.554	$191.55	$191.55	$191.60
Purchase #2	$12.41	3.507%	$12.8452	$12.85	$12.85	$12.80
Purchase #3	$40.58	12.284%	$45.5648	$45.56	$45.55	$45.60
Purchase #4	$191.64	10.834%	$212.4023	$212.40	$212.40	$212.40
Purchase #5	$26.60	6.527%	$28.3362	$28.34	$28.35	$28.30
Purchase #6	$215.88	4.757%	$226.1494	$226.15	$226.15	$226.10
Purchase #7	$40.52	11.481%	$45.1721	$45.17	$45.15	$45.20
7 purchase totals =	$704.51		$762.0240	$762.02	$762.00	$762.00