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	$47.59	11.493%	$53.0595	$53.06	$53.05	$53.10
Purchase #2	$156.98	7.560%	$168.8477	$168.85	$168.85	$168.80
Purchase #3	$210.63	3.484%	$217.9683	$217.97	$217.95	$218.00
Purchase #4	$93.54	11.446%	$104.2466	$104.25	$104.25	$104.20
Purchase #5	$81.51	13.336%	$92.3802	$92.38	$92.40	$92.40
Purchase #6	$235.67	5.851%	$249.4591	$249.46	$249.45	$249.50
Purchase #7	$141.82	11.647%	$158.3378	$158.34	$158.35	$158.30
7 purchase totals =	$967.74		$1,044.2992	$1,044.31	$1,044.30	$1,044.30