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	$191.96	9.555%	$210.3018	$210.30	$210.30	$210.30
Purchase #2	$200.95	8.373%	$217.7755	$217.78	$217.80	$217.80
Purchase #3	$33.82	7.187%	$36.2506	$36.25	$36.25	$36.30
Purchase #4	$41.52	11.268%	$46.1985	$46.20	$46.20	$46.20
Purchase #5	$89.28	7.106%	$95.6242	$95.62	$95.60	$95.60
Purchase #6	$185.30	11.129%	$205.922	$205.92	$205.90	$205.90
Purchase #7	$81.85	9.683%	$89.7755	$89.78	$89.80	$89.80
7 purchase totals =	$824.68		$901.8481	$901.85	$901.85	$901.90