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	$237.39	7.117%	$254.285	$254.29	$254.30	$254.30
Purchase #2	$13.85	5.542%	$14.6176	$14.62	$14.60	$14.60
Purchase #3	$216.31	13.546%	$245.6114	$245.61	$245.60	$245.60
Purchase #4	$102.29	9.710%	$112.2224	$112.22	$112.20	$112.20
Purchase #5	$54.40	11.158%	$60.47	$60.47	$60.45	$60.50
Purchase #6	$219.52	10.154%	$241.8101	$241.81	$241.80	$241.80
Purchase #7	$79.47	4.587%	$83.1153	$83.12	$83.10	$83.10
7 purchase totals =	$923.23		$1,012.1318	$1,012.14	$1,012.05	$1,012.10