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	$115.60	12.851%	$130.4558	$130.46	$130.45	$130.50
Purchase #2	$35.79	4.781%	$37.5011	$37.50	$37.50	$37.50
Purchase #3	$162.95	3.701%	$168.9808	$168.98	$169.00	$169.00
Purchase #4	$37.32	9.447%	$40.8456	$40.85	$40.85	$40.80
Purchase #5	$84.59	9.762%	$92.8477	$92.85	$92.85	$92.80
Purchase #6	$9.65	11.792%	$10.7879	$10.79	$10.80	$10.80
Purchase #7	$226.56	10.728%	$250.8654	$250.87	$250.85	$250.90
7 purchase totals =	$672.46		$732.2843	$732.30	$732.30	$732.30