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	$196.40	13.705%	$223.3166	$223.32	$223.30	$223.30
Purchase #2	$224.76	3.115%	$231.7613	$231.76	$231.75	$231.80
Purchase #3	$42.31	9.694%	$46.4115	$46.41	$46.40	$46.40
Purchase #4	$9.37	12.249%	$10.5177	$10.52	$10.50	$10.50
Purchase #5	$146.84	10.717%	$162.5768	$162.58	$162.60	$162.60
Purchase #6	$42.25	12.809%	$47.6618	$47.66	$47.65	$47.70
Purchase #7	$175.63	11.645%	$196.0821	$196.08	$196.10	$196.10
7 purchase totals =	$837.56		$918.3278	$918.33	$918.30	$918.40