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	$193.85	11.616%	$216.3676	$216.37	$216.35	$216.40
Purchase #2	$249.66	7.164%	$267.5456	$267.55	$267.55	$267.50
Purchase #3	$64.84	5.724%	$68.5514	$68.55	$68.55	$68.60
Purchase #4	$38.97	8.573%	$42.3109	$42.31	$42.30	$42.30
Purchase #5	$114.53	8.222%	$123.9467	$123.95	$123.95	$123.90
Purchase #6	$172.95	11.529%	$192.8894	$192.89	$192.90	$192.90
Purchase #7	$99.57	8.150%	$107.685	$107.69	$107.70	$107.70
7 purchase totals =	$934.37		$1,019.2966	$1,019.31	$1,019.30	$1,019.30