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	$241.58	7.503%	$259.7057	$259.71	$259.70	$259.70
Purchase #2	$115.73	8.112%	$125.118	$125.12	$125.10	$125.10
Purchase #3	$240.98	4.456%	$251.7181	$251.72	$251.70	$251.70
Purchase #4	$109.93	12.427%	$123.591	$123.59	$123.60	$123.60
Purchase #5	$94.69	10.413%	$104.5501	$104.55	$104.55	$104.60
Purchase #6	$20.80	4.104%	$21.6536	$21.65	$21.65	$21.70
Purchase #7	$117.54	5.468%	$123.9671	$123.97	$123.95	$124.00
7 purchase totals =	$941.25		$1,010.3036	$1,010.31	$1,010.25	$1,010.40