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	$190.77	12.557%	$214.725	$214.73	$214.75	$214.70
Purchase #2	$31.91	4.204%	$33.2515	$33.25	$33.25	$33.30
Purchase #3	$213.97	13.209%	$242.2333	$242.23	$242.25	$242.20
Purchase #4	$152.57	13.296%	$172.8557	$172.86	$172.85	$172.90
Purchase #5	$244.42	5.802%	$258.6012	$258.60	$258.60	$258.60
Purchase #6	$212.78	7.557%	$228.8598	$228.86	$228.85	$228.90
Purchase #7	$211.49	7.476%	$227.301	$227.30	$227.30	$227.30
7 purchase totals =	$1,257.91		$1,377.8275	$1,377.83	$1,377.85	$1,377.90