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	$244.52	9.502%	$267.7543	$267.75	$267.75	$267.80
Purchase #2	$144.32	9.683%	$158.2945	$158.29	$158.30	$158.30
Purchase #3	$189.55	3.641%	$196.4515	$196.45	$196.45	$196.50
Purchase #4	$27.93	9.209%	$30.5021	$30.50	$30.50	$30.50
Purchase #5	$14.37	6.781%	$15.3444	$15.34	$15.35	$15.30
Purchase #6	$168.71	6.106%	$179.0114	$179.01	$179.00	$179.00
Purchase #7	$94.55	3.786%	$98.1297	$98.13	$98.15	$98.10
7 purchase totals =	$883.95		$945.4879	$945.47	$945.50	$945.50