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	$117.69	7.215%	$126.1813	$126.18	$126.20	$126.20
Purchase #2	$198.46	12.615%	$223.4957	$223.50	$223.50	$223.50
Purchase #3	$36.38	13.846%	$41.4172	$41.42	$41.40	$41.40
Purchase #4	$231.58	5.471%	$244.2497	$244.25	$244.25	$244.20
Purchase #5	$171.86	4.595%	$179.757	$179.76	$179.75	$179.80
Purchase #6	$80.70	12.607%	$90.8738	$90.87	$90.85	$90.90
Purchase #7	$139.55	10.197%	$153.7799	$153.78	$153.80	$153.80
7 purchase totals =	$976.22		$1,059.7546	$1,059.76	$1,059.75	$1,059.80