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	$87.40	9.789%	$95.9556	$95.96	$95.95	$96.00
Purchase #2	$66.30	6.497%	$70.6075	$70.61	$70.60	$70.60
Purchase #3	$223.30	7.777%	$240.666	$240.67	$240.65	$240.70
Purchase #4	$195.93	4.463%	$204.6744	$204.67	$204.65	$204.70
Purchase #5	$91.40	12.784%	$103.0846	$103.08	$103.10	$103.10
Purchase #6	$83.57	8.619%	$90.7729	$90.77	$90.75	$90.80
Purchase #7	$209.51	7.677%	$225.5941	$225.59	$225.60	$225.60
7 purchase totals =	$957.41		$1,031.3551	$1,031.35	$1,031.30	$1,031.50