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	$201.53	10.179%	$222.0437	$222.04	$222.05	$222.00
Purchase #2	$180.27	4.509%	$188.3984	$188.40	$188.40	$188.40
Purchase #3	$38.73	10.378%	$42.7494	$42.75	$42.75	$42.70
Purchase #4	$239.89	3.548%	$248.4013	$248.40	$248.40	$248.40
Purchase #5	$201.52	7.832%	$217.303	$217.30	$217.30	$217.30
Purchase #6	$211.96	3.240%	$218.8275	$218.83	$218.85	$218.80
Purchase #7	$41.56	8.399%	$45.0506	$45.05	$45.05	$45.10
7 purchase totals =	$1,115.46		$1,182.7739	$1,182.77	$1,182.80	$1,182.70