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	$191.73	8.708%	$208.4258	$208.43	$208.45	$208.40
Purchase #2	$75.53	5.332%	$79.5573	$79.56	$79.55	$79.60
Purchase #3	$142.98	7.391%	$153.5477	$153.55	$153.55	$153.50
Purchase #4	$215.92	7.261%	$231.598	$231.60	$231.60	$231.60
Purchase #5	$131.46	10.338%	$145.0503	$145.05	$145.05	$145.10
Purchase #6	$128.92	11.720%	$144.0294	$144.03	$144.05	$144.00
Purchase #7	$91.85	12.741%	$103.5526	$103.55	$103.55	$103.60
7 purchase totals =	$978.39		$1,065.7611	$1,065.77	$1,065.80	$1,065.80