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	$114.64	9.437%	$125.4586	$125.46	$125.45	$125.50
Purchase #2	$250.98	3.572%	$259.945	$259.95	$259.95	$259.90
Purchase #3	$240.53	4.153%	$250.5192	$250.52	$250.50	$250.50
Purchase #4	$96.32	6.269%	$102.3583	$102.36	$102.35	$102.40
Purchase #5	$249.32	10.126%	$274.5661	$274.57	$274.55	$274.60
Purchase #6	$84.98	6.714%	$90.6856	$90.69	$90.70	$90.70
Purchase #7	$12.31	3.680%	$12.763	$12.76	$12.75	$12.80
7 purchase totals =	$1,049.08		$1,116.2958	$1,116.31	$1,116.25	$1,116.40