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	$205.37	13.641%	$233.3845	$233.38	$233.40	$233.40
Purchase #2	$31.74	6.366%	$33.7606	$33.76	$33.75	$33.80
Purchase #3	$202.79	10.694%	$224.4764	$224.48	$224.50	$224.50
Purchase #4	$45.78	4.609%	$47.89	$47.89	$47.90	$47.90
Purchase #5	$152.62	5.794%	$161.4628	$161.46	$161.45	$161.50
Purchase #6	$127.97	11.477%	$142.6571	$142.66	$142.65	$142.70
Purchase #7	$166.84	7.159%	$178.7841	$178.78	$178.80	$178.80
7 purchase totals =	$933.11		$1,022.4155	$1,022.41	$1,022.45	$1,022.60