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	$97.75	8.460%	$106.0197	$106.02	$106.00	$106.00
Purchase #2	$137.66	10.229%	$151.7412	$151.74	$151.75	$151.70
Purchase #3	$31.43	6.380%	$33.4352	$33.44	$33.45	$33.40
Purchase #4	$208.54	4.407%	$217.7304	$217.73	$217.75	$217.70
Purchase #5	$108.86	4.119%	$113.3439	$113.34	$113.35	$113.30
Purchase #6	$123.63	13.675%	$140.5364	$140.54	$140.55	$140.50
Purchase #7	$88.93	12.813%	$100.3246	$100.32	$100.30	$100.30
7 purchase totals =	$796.80		$863.1314	$863.13	$863.15	$862.90