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	$61.30	10.577%	$67.7837	$67.78	$67.80	$67.80
Purchase #2	$189.46	4.302%	$197.6106	$197.61	$197.60	$197.60
Purchase #3	$65.52	7.297%	$70.301	$70.30	$70.30	$70.30
Purchase #4	$36.77	8.301%	$39.8223	$39.82	$39.80	$39.80
Purchase #5	$167.51	12.855%	$189.0434	$189.04	$189.05	$189.00
Purchase #6	$177.69	7.752%	$191.4645	$191.46	$191.45	$191.50
Purchase #7	$244.51	5.750%	$258.5693	$258.57	$258.55	$258.60
7 purchase totals =	$942.76		$1,014.5948	$1,014.58	$1,014.55	$1,014.60