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	$149.70	3.427%	$154.8302	$154.83	$154.85	$154.80
Purchase #2	$238.45	13.686%	$271.0843	$271.08	$271.10	$271.10
Purchase #3	$60.63	11.478%	$67.5891	$67.59	$67.60	$67.60
Purchase #4	$140.42	5.271%	$147.8215	$147.82	$147.80	$147.80
Purchase #5	$148.27	5.650%	$156.6473	$156.65	$156.65	$156.60
Purchase #6	$188.48	10.856%	$208.9414	$208.94	$208.95	$208.90
Purchase #7	$139.72	5.187%	$146.9673	$146.97	$146.95	$147.00
7 purchase totals =	$1,065.67		$1,153.8811	$1,153.88	$1,153.90	$1,153.80