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	$211.27	7.715%	$227.5695	$227.57	$227.55	$227.60
Purchase #2	$41.64	5.243%	$43.8232	$43.82	$43.80	$43.80
Purchase #3	$249.33	7.728%	$268.5982	$268.60	$268.60	$268.60
Purchase #4	$222.95	10.296%	$245.9049	$245.90	$245.90	$245.90
Purchase #5	$230.92	7.858%	$249.0657	$249.07	$249.05	$249.10
Purchase #6	$249.61	10.187%	$275.0378	$275.04	$275.05	$275.00
Purchase #7	$48.33	12.348%	$54.2978	$54.30	$54.30	$54.30
7 purchase totals =	$1,254.05		$1,364.2971	$1,364.30	$1,364.25	$1,364.30