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	$116.63	12.359%	$131.0443	$131.04	$131.05	$131.00
Purchase #2	$136.96	12.538%	$154.132	$154.13	$154.15	$154.10
Purchase #3	$115.27	7.446%	$123.853	$123.85	$123.85	$123.90
Purchase #4	$119.68	5.340%	$126.0709	$126.07	$126.05	$126.10
Purchase #5	$209.69	12.684%	$236.2871	$236.29	$236.30	$236.30
Purchase #6	$244.56	4.474%	$255.5016	$255.50	$255.50	$255.50
Purchase #7	$60.77	11.838%	$67.964	$67.96	$67.95	$68.00
7 purchase totals =	$1,003.56		$1,094.8529	$1,094.84	$1,094.85	$1,094.90