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	$87.83	7.862%	$94.7352	$94.74	$94.75	$94.70
Purchase #2	$174.74	12.389%	$196.3885	$196.39	$196.40	$196.40
Purchase #3	$184.96	11.773%	$206.7353	$206.74	$206.75	$206.70
Purchase #4	$34.83	12.155%	$39.0636	$39.06	$39.05	$39.10
Purchase #5	$198.72	8.587%	$215.7841	$215.78	$215.80	$215.80
Purchase #6	$31.42	10.804%	$34.8146	$34.81	$34.80	$34.80
Purchase #7	$211.80	12.572%	$238.4275	$238.43	$238.45	$238.40
7 purchase totals =	$924.30		$1,025.9488	$1,025.95	$1,026.00	$1,025.90