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	$87.26	9.435%	$95.493	$95.49	$95.50	$95.50
Purchase #2	$87.26	8.136%	$94.3595	$94.36	$94.35	$94.40
Purchase #3	$71.82	10.376%	$79.272	$79.27	$79.25	$79.30
Purchase #4	$73.50	12.386%	$82.6037	$82.60	$82.60	$82.60
Purchase #5	$214.92	11.724%	$240.1172	$240.12	$240.10	$240.10
Purchase #6	$212.34	12.267%	$238.3877	$238.39	$238.40	$238.40
Purchase #7	$65.28	9.684%	$71.6017	$71.60	$71.60	$71.60
7 purchase totals =	$812.38		$901.8348	$901.83	$901.80	$901.90