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	$202.34	11.438%	$225.4836	$225.48	$225.50	$225.50
Purchase #2	$66.94	8.499%	$72.6292	$72.63	$72.65	$72.60
Purchase #3	$138.46	7.333%	$148.6133	$148.61	$148.60	$148.60
Purchase #4	$83.37	3.767%	$86.5105	$86.51	$86.50	$86.50
Purchase #5	$197.60	10.773%	$218.8874	$218.89	$218.90	$218.90
Purchase #6	$45.94	6.195%	$48.786	$48.79	$48.80	$48.80
Purchase #7	$233.61	10.810%	$258.8632	$258.86	$258.85	$258.90
7 purchase totals =	$968.26		$1,059.7732	$1,059.77	$1,059.80	$1,059.80