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	$192.78	6.831%	$205.9488	$205.95	$205.95	$205.90
Purchase #2	$145.59	7.233%	$156.1205	$156.12	$156.10	$156.10
Purchase #3	$13.76	11.765%	$15.3789	$15.38	$15.40	$15.40
Purchase #4	$62.90	7.130%	$67.3848	$67.38	$67.40	$67.40
Purchase #5	$160.52	8.116%	$173.5478	$173.55	$173.55	$173.50
Purchase #6	$193.26	8.732%	$210.1355	$210.14	$210.15	$210.10
Purchase #7	$190.29	11.398%	$211.9793	$211.98	$212.00	$212.00
7 purchase totals =	$959.10		$1,040.4956	$1,040.50	$1,040.55	$1,040.40