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	$205.77	8.192%	$222.6267	$222.63	$222.65	$222.60
Purchase #2	$171.59	6.345%	$182.4774	$182.48	$182.50	$182.50
Purchase #3	$171.90	10.392%	$189.7638	$189.76	$189.75	$189.80
Purchase #4	$63.48	5.474%	$66.9549	$66.95	$66.95	$67.00
Purchase #5	$24.27	13.669%	$27.5875	$27.59	$27.60	$27.60
Purchase #6	$169.69	10.221%	$187.034	$187.03	$187.05	$187.00
Purchase #7	$131.26	12.447%	$147.5979	$147.60	$147.60	$147.60
7 purchase totals =	$937.96		$1,024.0422	$1,024.04	$1,024.10	$1,024.10