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	$187.92	10.156%	$207.0052	$207.01	$207.00	$207.00
Purchase #2	$193.50	12.325%	$217.3489	$217.35	$217.35	$217.30
Purchase #3	$77.61	6.787%	$82.8774	$82.88	$82.90	$82.90
Purchase #4	$243.58	6.540%	$259.5101	$259.51	$259.50	$259.50
Purchase #5	$165.70	4.776%	$173.6138	$173.61	$173.60	$173.60
Purchase #6	$15.58	7.206%	$16.7027	$16.70	$16.70	$16.70
Purchase #7	$100.78	3.152%	$103.9566	$103.96	$103.95	$104.00
7 purchase totals =	$984.67		$1,061.0147	$1,061.02	$1,061.00	$1,061.00