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	$200.81	7.439%	$215.7483	$215.75	$215.75	$215.70
Purchase #2	$187.72	5.601%	$198.2342	$198.23	$198.25	$198.20
Purchase #3	$94.48	11.541%	$105.3839	$105.38	$105.40	$105.40
Purchase #4	$11.48	3.452%	$11.8763	$11.88	$11.90	$11.90
Purchase #5	$239.86	9.349%	$262.2845	$262.28	$262.30	$262.30
Purchase #6	$116.96	9.808%	$128.4314	$128.43	$128.45	$128.40
Purchase #7	$149.87	13.767%	$170.5026	$170.50	$170.50	$170.50
7 purchase totals =	$1,001.18		$1,092.4612	$1,092.45	$1,092.55	$1,092.40