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	$54.88	13.722%	$62.4106	$62.41	$62.40	$62.40
Purchase #2	$141.57	4.752%	$148.2974	$148.30	$148.30	$148.30
Purchase #3	$156.50	7.394%	$168.0716	$168.07	$168.05	$168.10
Purchase #4	$37.59	3.180%	$38.7854	$38.79	$38.80	$38.80
Purchase #5	$187.55	12.675%	$211.322	$211.32	$211.30	$211.30
Purchase #6	$145.47	10.768%	$161.1342	$161.13	$161.15	$161.10
Purchase #7	$153.82	12.165%	$172.5322	$172.53	$172.55	$172.50
7 purchase totals =	$877.38		$962.5534	$962.55	$962.55	$962.50