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	$211.44	11.566%	$235.8952	$235.90	$235.90	$235.90
Purchase #2	$8.78	5.429%	$9.2567	$9.26	$9.25	$9.30
Purchase #3	$90.92	9.797%	$99.8274	$99.83	$99.85	$99.80
Purchase #4	$55.88	11.663%	$62.3973	$62.40	$62.40	$62.40
Purchase #5	$105.95	3.418%	$109.5714	$109.57	$109.55	$109.60
Purchase #6	$105.51	3.349%	$109.0435	$109.04	$109.05	$109.00
Purchase #7	$123.99	10.105%	$136.5192	$136.52	$136.50	$136.50
7 purchase totals =	$702.47		$762.5107	$762.52	$762.50	$762.50