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	$196.55	10.142%	$216.4841	$216.48	$216.50	$216.50
Purchase #2	$69.99	5.152%	$73.5959	$73.60	$73.60	$73.60
Purchase #3	$107.27	4.209%	$111.785	$111.79	$111.80	$111.80
Purchase #4	$13.53	10.386%	$14.9352	$14.94	$14.95	$14.90
Purchase #5	$99.51	7.483%	$106.9563	$106.96	$106.95	$107.00
Purchase #6	$205.50	6.315%	$218.4773	$218.48	$218.50	$218.50
Purchase #7	$101.33	7.701%	$109.1334	$109.13	$109.15	$109.10
7 purchase totals =	$793.68		$851.3672	$851.38	$851.45	$851.40