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	$107.75	4.551%	$112.6537	$112.65	$112.65	$112.70
Purchase #2	$216.59	13.694%	$246.2498	$246.25	$246.25	$246.20
Purchase #3	$86.57	10.205%	$95.4045	$95.40	$95.40	$95.40
Purchase #4	$241.57	7.680%	$260.1226	$260.12	$260.10	$260.10
Purchase #5	$17.86	3.466%	$18.479	$18.48	$18.50	$18.50
Purchase #6	$187.51	10.164%	$206.5685	$206.57	$206.55	$206.60
Purchase #7	$79.98	7.405%	$85.9025	$85.90	$85.90	$85.90
7 purchase totals =	$937.83		$1,025.3806	$1,025.37	$1,025.35	$1,025.40