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	$162.84	11.602%	$181.7327	$181.73	$181.75	$181.70
Purchase #2	$26.89	7.385%	$28.8758	$28.88	$28.90	$28.90
Purchase #3	$212.41	4.742%	$222.4825	$222.48	$222.50	$222.50
Purchase #4	$61.90	8.382%	$67.0885	$67.09	$67.10	$67.10
Purchase #5	$29.86	13.808%	$33.9831	$33.98	$34.00	$34.00
Purchase #6	$191.82	12.818%	$216.4075	$216.41	$216.40	$216.40
Purchase #7	$231.55	11.745%	$258.7455	$258.75	$258.75	$258.70
7 purchase totals =	$917.27		$1,009.3156	$1,009.32	$1,009.40	$1,009.30