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	$181.98	7.106%	$194.9115	$194.91	$194.90	$194.90
Purchase #2	$92.70	13.749%	$105.4453	$105.45	$105.45	$105.40
Purchase #3	$242.54	11.435%	$270.2744	$270.27	$270.25	$270.30
Purchase #4	$157.96	10.516%	$174.5711	$174.57	$174.55	$174.60
Purchase #5	$37.84	3.729%	$39.2511	$39.25	$39.25	$39.30
Purchase #6	$144.81	8.367%	$156.9263	$156.93	$156.95	$156.90
Purchase #7	$103.63	8.487%	$112.4251	$112.43	$112.45	$112.40
7 purchase totals =	$961.46		$1,053.8048	$1,053.81	$1,053.80	$1,053.80