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	$12.55	13.838%	$14.2867	$14.29	$14.30	$14.30
Purchase #2	$98.52	9.727%	$108.103	$108.10	$108.10	$108.10
Purchase #3	$246.26	6.214%	$261.5626	$261.56	$261.55	$261.60
Purchase #4	$142.61	8.868%	$155.2567	$155.26	$155.25	$155.30
Purchase #5	$164.55	12.657%	$185.3771	$185.38	$185.40	$185.40
Purchase #6	$138.33	4.468%	$144.5106	$144.51	$144.50	$144.50
Purchase #7	$132.67	6.571%	$141.3877	$141.39	$141.40	$141.40
7 purchase totals =	$935.49		$1,010.4844	$1,010.49	$1,010.50	$1,010.60