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	$64.31	5.127%	$67.6072	$67.61	$67.60	$67.60
Purchase #2	$232.74	12.600%	$262.0652	$262.07	$262.05	$262.10
Purchase #3	$103.94	4.358%	$108.4697	$108.47	$108.45	$108.50
Purchase #4	$54.91	11.691%	$61.3295	$61.33	$61.35	$61.30
Purchase #5	$120.87	10.786%	$133.907	$133.91	$133.90	$133.90
Purchase #6	$215.66	8.389%	$233.7517	$233.75	$233.75	$233.80
Purchase #7	$178.92	4.775%	$187.4634	$187.46	$187.45	$187.50
7 purchase totals =	$971.35		$1,054.5937	$1,054.60	$1,054.55	$1,054.70