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	$152.74	9.691%	$167.542	$167.54	$167.55	$167.50
Purchase #2	$57.92	7.193%	$62.0862	$62.09	$62.10	$62.10
Purchase #3	$100.63	4.757%	$105.417	$105.42	$105.40	$105.40
Purchase #4	$231.66	8.602%	$251.5874	$251.59	$251.60	$251.60
Purchase #5	$60.71	11.389%	$67.6243	$67.62	$67.60	$67.60
Purchase #6	$242.42	7.446%	$260.4706	$260.47	$260.45	$260.50
Purchase #7	$101.43	8.358%	$109.9075	$109.91	$109.90	$109.90
7 purchase totals =	$947.51		$1,024.6350	$1,024.64	$1,024.60	$1,024.60