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	$56.95	7.868%	$61.4308	$61.43	$61.45	$61.40
Purchase #2	$79.98	9.802%	$87.8196	$87.82	$87.80	$87.80
Purchase #3	$164.39	8.697%	$178.687	$178.69	$178.70	$178.70
Purchase #4	$140.59	8.493%	$152.5303	$152.53	$152.55	$152.50
Purchase #5	$223.66	11.730%	$249.8953	$249.90	$249.90	$249.90
Purchase #6	$232.90	9.646%	$255.3655	$255.37	$255.35	$255.40
Purchase #7	$68.62	5.835%	$72.624	$72.62	$72.60	$72.60
7 purchase totals =	$967.09		$1,058.3525	$1,058.36	$1,058.35	$1,058.30