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	$143.50	10.487%	$158.5488	$158.55	$158.55	$158.50
Purchase #2	$123.41	5.343%	$130.0038	$130.00	$130.00	$130.00
Purchase #3	$121.66	8.199%	$131.6349	$131.63	$131.65	$131.60
Purchase #4	$191.63	8.427%	$207.7787	$207.78	$207.80	$207.80
Purchase #5	$150.35	4.383%	$156.9398	$156.94	$156.95	$156.90
Purchase #6	$185.36	12.213%	$207.998	$208.00	$208.00	$208.00
Purchase #7	$89.66	4.301%	$93.5163	$93.52	$93.50	$93.50
7 purchase totals =	$1,005.57		$1,086.4203	$1,086.42	$1,086.45	$1,086.30