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	$185.55	11.312%	$206.5394	$206.54	$206.55	$206.50
Purchase #2	$96.63	13.328%	$109.5088	$109.51	$109.50	$109.50
Purchase #3	$13.86	3.545%	$14.3513	$14.35	$14.35	$14.40
Purchase #4	$153.44	9.821%	$168.5093	$168.51	$168.50	$168.50
Purchase #5	$185.54	6.106%	$196.8691	$196.87	$196.85	$196.90
Purchase #6	$210.74	13.384%	$238.9454	$238.95	$238.95	$238.90
Purchase #7	$139.69	4.145%	$145.4802	$145.48	$145.50	$145.50
7 purchase totals =	$985.45		$1,080.2035	$1,080.21	$1,080.20	$1,080.20