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	$216.69	8.729%	$235.6049	$235.60	$235.60	$235.60
Purchase #2	$92.69	11.726%	$103.5588	$103.56	$103.55	$103.60
Purchase #3	$125.69	6.502%	$133.8624	$133.86	$133.85	$133.90
Purchase #4	$28.66	10.186%	$31.5793	$31.58	$31.60	$31.60
Purchase #5	$194.59	11.396%	$216.7655	$216.77	$216.75	$216.80
Purchase #6	$116.36	8.780%	$126.5764	$126.58	$126.60	$126.60
Purchase #7	$159.79	5.600%	$168.7382	$168.74	$168.75	$168.70
7 purchase totals =	$934.47		$1,016.6855	$1,016.69	$1,016.70	$1,016.80