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	$186.44	5.585%	$196.8527	$196.85	$196.85	$196.90
Purchase #2	$223.71	9.627%	$245.2466	$245.25	$245.25	$245.20
Purchase #3	$92.35	7.548%	$99.3206	$99.32	$99.30	$99.30
Purchase #4	$19.27	9.261%	$21.0546	$21.05	$21.05	$21.10
Purchase #5	$101.98	10.780%	$112.9734	$112.97	$112.95	$113.00
Purchase #6	$163.56	9.389%	$178.9166	$178.92	$178.90	$178.90
Purchase #7	$177.47	5.672%	$187.5361	$187.54	$187.55	$187.50
7 purchase totals =	$964.78		$1,041.9006	$1,041.90	$1,041.85	$1,041.90