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	$151.50	4.323%	$158.0493	$158.05	$158.05	$158.00
Purchase #2	$126.70	11.128%	$140.7992	$140.80	$140.80	$140.80
Purchase #3	$43.48	3.609%	$45.0492	$45.05	$45.05	$45.00
Purchase #4	$246.40	3.538%	$255.1176	$255.12	$255.10	$255.10
Purchase #5	$91.97	9.195%	$100.4266	$100.43	$100.45	$100.40
Purchase #6	$63.51	10.765%	$70.3469	$70.35	$70.35	$70.30
Purchase #7	$75.57	10.395%	$83.4255	$83.43	$83.45	$83.40
7 purchase totals =	$799.13		$853.2143	$853.23	$853.25	$853.00