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	$201.95	6.257%	$214.586	$214.59	$214.60	$214.60
Purchase #2	$112.84	5.858%	$119.4502	$119.45	$119.45	$119.50
Purchase #3	$238.87	13.675%	$271.5355	$271.54	$271.55	$271.50
Purchase #4	$41.92	7.363%	$45.0066	$45.01	$45.00	$45.00
Purchase #5	$231.60	5.532%	$244.4121	$244.41	$244.40	$244.40
Purchase #6	$127.59	3.120%	$131.5708	$131.57	$131.55	$131.60
Purchase #7	$88.74	3.154%	$91.5389	$91.54	$91.55	$91.50
7 purchase totals =	$1,043.51		$1,118.1001	$1,118.11	$1,118.10	$1,118.10