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	$210.33	5.838%	$222.6091	$222.61	$222.60	$222.60
Purchase #2	$96.35	3.359%	$99.5864	$99.59	$99.60	$99.60
Purchase #3	$101.56	10.513%	$112.237	$112.24	$112.25	$112.20
Purchase #4	$115.26	13.796%	$131.1613	$131.16	$131.15	$131.20
Purchase #5	$96.63	3.409%	$99.9241	$99.92	$99.90	$99.90
Purchase #6	$133.77	7.508%	$143.8135	$143.81	$143.80	$143.80
Purchase #7	$208.25	4.405%	$217.4234	$217.42	$217.40	$217.40
7 purchase totals =	$962.15		$1,026.7548	$1,026.75	$1,026.70	$1,026.70