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	$207.66	12.375%	$233.3579	$233.36	$233.35	$233.40
Purchase #2	$86.65	4.254%	$90.3361	$90.34	$90.35	$90.30
Purchase #3	$10.55	7.566%	$11.3482	$11.35	$11.35	$11.30
Purchase #4	$61.67	13.375%	$69.9184	$69.92	$69.90	$69.90
Purchase #5	$126.78	11.228%	$141.0149	$141.01	$141.00	$141.00
Purchase #6	$55.54	11.475%	$61.9132	$61.91	$61.90	$61.90
Purchase #7	$206.79	5.168%	$217.4769	$217.48	$217.50	$217.50
7 purchase totals =	$755.64		$825.3656	$825.37	$825.35	$825.30