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	$164.91	8.615%	$179.117	$179.12	$179.10	$179.10
Purchase #2	$75.60	4.205%	$78.779	$78.78	$78.80	$78.80
Purchase #3	$199.87	9.119%	$218.0961	$218.10	$218.10	$218.10
Purchase #4	$244.39	9.434%	$267.4458	$267.45	$267.45	$267.40
Purchase #5	$86.95	10.710%	$96.2623	$96.26	$96.25	$96.30
Purchase #6	$40.41	8.176%	$43.7139	$43.71	$43.70	$43.70
Purchase #7	$245.77	5.331%	$258.872	$258.87	$258.85	$258.90
7 purchase totals =	$1,057.90		$1,142.2861	$1,142.29	$1,142.25	$1,142.30