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	$239.56	6.234%	$254.4942	$254.49	$254.50	$254.50
Purchase #2	$73.82	5.801%	$78.1023	$78.10	$78.10	$78.10
Purchase #3	$221.85	9.440%	$242.7926	$242.79	$242.80	$242.80
Purchase #4	$67.40	9.235%	$73.6244	$73.62	$73.60	$73.60
Purchase #5	$75.83	13.571%	$86.1209	$86.12	$86.10	$86.10
Purchase #6	$87.37	8.535%	$94.827	$94.83	$94.85	$94.80
Purchase #7	$192.64	11.385%	$214.5721	$214.57	$214.55	$214.60
7 purchase totals =	$958.47		$1,044.5335	$1,044.52	$1,044.50	$1,044.50