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	$157.89	4.161%	$164.4598	$164.46	$164.45	$164.50
Purchase #2	$19.73	4.128%	$20.5445	$20.54	$20.55	$20.50
Purchase #3	$7.35	5.697%	$7.7687	$7.77	$7.75	$7.80
Purchase #4	$67.98	3.687%	$70.4864	$70.49	$70.50	$70.50
Purchase #5	$211.91	12.324%	$238.0258	$238.03	$238.05	$238.00
Purchase #6	$115.50	13.250%	$130.8038	$130.80	$130.80	$130.80
Purchase #7	$109.35	13.478%	$124.0882	$124.09	$124.10	$124.10
7 purchase totals =	$689.71		$756.1772	$756.18	$756.20	$756.20