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	$46.54	10.768%	$51.5514	$51.55	$51.55	$51.60
Purchase #2	$62.92	12.851%	$71.0058	$71.01	$71.00	$71.00
Purchase #3	$173.42	3.633%	$179.7203	$179.72	$179.70	$179.70
Purchase #4	$120.40	3.516%	$124.6333	$124.63	$124.65	$124.60
Purchase #5	$38.33	12.494%	$43.119	$43.12	$43.10	$43.10
Purchase #6	$173.90	5.861%	$184.0923	$184.09	$184.10	$184.10
Purchase #7	$54.54	10.807%	$60.4341	$60.43	$60.45	$60.40
7 purchase totals =	$670.05		$714.5562	$714.55	$714.55	$714.50