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	$215.46	3.470%	$222.9365	$222.94	$222.95	$222.90
Purchase #2	$19.56	4.757%	$20.4905	$20.49	$20.50	$20.50
Purchase #3	$165.87	13.670%	$188.5444	$188.54	$188.55	$188.50
Purchase #4	$234.40	9.328%	$256.2648	$256.26	$256.25	$256.30
Purchase #5	$228.98	6.511%	$243.8889	$243.89	$243.90	$243.90
Purchase #6	$69.48	8.787%	$75.5852	$75.59	$75.60	$75.60
Purchase #7	$16.93	5.720%	$17.8984	$17.90	$17.90	$17.90
7 purchase totals =	$950.68		$1,025.6087	$1,025.61	$1,025.65	$1,025.60