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	$186.83	7.257%	$200.3883	$200.39	$200.40	$200.40
Purchase #2	$173.32	7.238%	$185.8649	$185.86	$185.85	$185.90
Purchase #3	$189.34	4.104%	$197.1105	$197.11	$197.10	$197.10
Purchase #4	$225.85	3.399%	$233.5266	$233.53	$233.55	$233.50
Purchase #5	$226.94	3.801%	$235.566	$235.57	$235.55	$235.60
Purchase #6	$174.93	13.225%	$198.0645	$198.06	$198.05	$198.10
Purchase #7	$232.35	3.660%	$240.854	$240.85	$240.85	$240.90
7 purchase totals =	$1,409.56		$1,491.3748	$1,491.37	$1,491.35	$1,491.50