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	$195.56	8.189%	$211.5744	$211.57	$211.55	$211.60
Purchase #2	$245.48	6.752%	$262.0548	$262.05	$262.05	$262.10
Purchase #3	$74.51	10.677%	$82.4654	$82.47	$82.45	$82.50
Purchase #4	$50.50	8.541%	$54.8132	$54.81	$54.80	$54.80
Purchase #5	$241.66	5.247%	$254.3399	$254.34	$254.35	$254.30
Purchase #6	$84.86	5.171%	$89.2481	$89.25	$89.25	$89.20
Purchase #7	$197.69	6.865%	$211.2614	$211.26	$211.25	$211.30
7 purchase totals =	$1,090.26		$1,165.7572	$1,165.75	$1,165.70	$1,165.80