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	$233.49	4.867%	$244.854	$244.85	$244.85	$244.90
Purchase #2	$41.25	3.115%	$42.5349	$42.53	$42.55	$42.50
Purchase #3	$184.83	6.295%	$196.465	$196.47	$196.45	$196.50
Purchase #4	$174.42	11.554%	$194.5725	$194.57	$194.55	$194.60
Purchase #5	$197.96	10.807%	$219.3535	$219.35	$219.35	$219.40
Purchase #6	$120.65	13.225%	$136.606	$136.61	$136.60	$136.60
Purchase #7	$105.81	7.854%	$114.1203	$114.12	$114.10	$114.10
7 purchase totals =	$1,058.41		$1,148.5062	$1,148.50	$1,148.45	$1,148.60