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	$94.60	13.330%	$107.2102	$107.21	$107.20	$107.20
Purchase #2	$150.29	9.301%	$164.2685	$164.27	$164.25	$164.30
Purchase #3	$41.82	9.630%	$45.8473	$45.85	$45.85	$45.80
Purchase #4	$91.97	4.113%	$95.7527	$95.75	$95.75	$95.80
Purchase #5	$228.43	11.868%	$255.5401	$255.54	$255.55	$255.50
Purchase #6	$235.26	4.386%	$245.5785	$245.58	$245.60	$245.60
Purchase #7	$100.81	10.368%	$111.262	$111.26	$111.25	$111.30
7 purchase totals =	$943.18		$1,025.4593	$1,025.46	$1,025.45	$1,025.50