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	$219.53	11.800%	$245.4345	$245.43	$245.45	$245.40
Purchase #2	$217.83	5.393%	$229.5776	$229.58	$229.60	$229.60
Purchase #3	$69.85	12.229%	$78.392	$78.39	$78.40	$78.40
Purchase #4	$164.62	13.147%	$186.2626	$186.26	$186.25	$186.30
Purchase #5	$206.90	5.810%	$218.9209	$218.92	$218.90	$218.90
Purchase #6	$57.61	12.700%	$64.9265	$64.93	$64.95	$64.90
Purchase #7	$169.63	12.268%	$190.4402	$190.44	$190.45	$190.40
7 purchase totals =	$1,105.97		$1,213.9543	$1,213.95	$1,214.00	$1,213.90