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	$60.64	4.445%	$63.3354	$63.34	$63.35	$63.30
Purchase #2	$53.69	4.262%	$55.9783	$55.98	$56.00	$56.00
Purchase #3	$215.96	11.446%	$240.6788	$240.68	$240.70	$240.70
Purchase #4	$140.54	13.790%	$159.9205	$159.92	$159.90	$159.90
Purchase #5	$139.52	3.263%	$144.0725	$144.07	$144.05	$144.10
Purchase #6	$83.78	8.706%	$91.0739	$91.07	$91.05	$91.10
Purchase #7	$39.47	7.816%	$42.555	$42.56	$42.55	$42.60
7 purchase totals =	$733.60		$797.6144	$797.62	$797.60	$797.70