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	$57.96	12.585%	$65.2543	$65.25	$65.25	$65.30
Purchase #2	$138.29	3.238%	$142.7678	$142.77	$142.75	$142.80
Purchase #3	$229.42	7.631%	$246.927	$246.93	$246.95	$246.90
Purchase #4	$82.83	7.552%	$89.0853	$89.09	$89.10	$89.10
Purchase #5	$200.47	9.367%	$219.248	$219.25	$219.25	$219.20
Purchase #6	$109.78	4.632%	$114.865	$114.87	$114.85	$114.90
Purchase #7	$174.46	3.764%	$181.0267	$181.03	$181.05	$181.00
7 purchase totals =	$993.21		$1,059.1741	$1,059.19	$1,059.20	$1,059.20