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	$182.69	9.249%	$199.587	$199.59	$199.60	$199.60
Purchase #2	$70.33	10.690%	$77.8483	$77.85	$77.85	$77.80
Purchase #3	$218.62	11.592%	$243.9624	$243.96	$243.95	$244.00
Purchase #4	$85.58	5.849%	$90.5856	$90.59	$90.60	$90.60
Purchase #5	$207.48	5.227%	$218.325	$218.33	$218.35	$218.30
Purchase #6	$47.53	12.417%	$53.4318	$53.43	$53.45	$53.40
Purchase #7	$195.84	8.151%	$211.8029	$211.80	$211.80	$211.80
7 purchase totals =	$1,008.07		$1,095.5430	$1,095.55	$1,095.60	$1,095.50