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	$43.60	4.261%	$45.4578	$45.46	$45.45	$45.50
Purchase #2	$127.26	12.381%	$143.0161	$143.02	$143.00	$143.00
Purchase #3	$164.60	9.684%	$180.5399	$180.54	$180.55	$180.50
Purchase #4	$158.35	5.661%	$167.3142	$167.31	$167.30	$167.30
Purchase #5	$177.78	12.669%	$200.3029	$200.30	$200.30	$200.30
Purchase #6	$97.46	9.176%	$106.4029	$106.40	$106.40	$106.40
Purchase #7	$201.89	7.531%	$217.0943	$217.09	$217.10	$217.10
7 purchase totals =	$970.94		$1,060.1281	$1,060.12	$1,060.10	$1,060.10