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	$182.64	7.574%	$196.4732	$196.47	$196.45	$196.50
Purchase #2	$43.93	5.595%	$46.3879	$46.39	$46.40	$46.40
Purchase #3	$203.75	7.383%	$218.7929	$218.79	$218.80	$218.80
Purchase #4	$149.42	8.741%	$162.4808	$162.48	$162.50	$162.50
Purchase #5	$96.80	6.344%	$102.941	$102.94	$102.95	$102.90
Purchase #6	$203.27	11.645%	$226.9408	$226.94	$226.95	$226.90
Purchase #7	$47.46	11.292%	$52.8192	$52.82	$52.80	$52.80
7 purchase totals =	$927.27		$1,006.8358	$1,006.83	$1,006.85	$1,006.80