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	$62.48	8.558%	$67.827	$67.83	$67.85	$67.80
Purchase #2	$77.82	3.196%	$80.3071	$80.31	$80.30	$80.30
Purchase #3	$90.84	13.488%	$103.0925	$103.09	$103.10	$103.10
Purchase #4	$159.35	4.484%	$166.4953	$166.50	$166.50	$166.50
Purchase #5	$154.49	8.289%	$167.2957	$167.30	$167.30	$167.30
Purchase #6	$85.63	3.353%	$88.5012	$88.50	$88.50	$88.50
Purchase #7	$67.62	4.457%	$70.6338	$70.63	$70.65	$70.60
7 purchase totals =	$698.23		$744.1526	$744.16	$744.20	$744.10