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	$63.48	9.426%	$69.4636	$69.46	$69.45	$69.50
Purchase #2	$213.58	9.846%	$234.6091	$234.61	$234.60	$234.60
Purchase #3	$99.90	13.644%	$113.5304	$113.53	$113.55	$113.50
Purchase #4	$217.27	7.600%	$233.7825	$233.78	$233.80	$233.80
Purchase #5	$222.52	3.776%	$230.9224	$230.92	$230.90	$230.90
Purchase #6	$141.77	6.829%	$151.4515	$151.45	$151.45	$151.50
Purchase #7	$18.38	5.433%	$19.3786	$19.38	$19.40	$19.40
7 purchase totals =	$976.90		$1,053.1381	$1,053.13	$1,053.15	$1,053.20