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	$117.28	7.839%	$126.4736	$126.47	$126.45	$126.50
Purchase #2	$240.73	3.683%	$249.5961	$249.60	$249.60	$249.60
Purchase #3	$62.67	5.872%	$66.35	$66.35	$66.35	$66.40
Purchase #4	$52.72	9.755%	$57.8628	$57.86	$57.85	$57.90
Purchase #5	$19.57	3.837%	$20.3209	$20.32	$20.30	$20.30
Purchase #6	$241.46	5.539%	$254.8345	$254.83	$254.85	$254.80
Purchase #7	$83.54	9.805%	$91.7311	$91.73	$91.75	$91.70
7 purchase totals =	$817.97		$867.1690	$867.16	$867.15	$867.20