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	$116.82	8.368%	$126.5955	$126.60	$126.60	$126.60
Purchase #2	$137.92	6.271%	$146.569	$146.57	$146.55	$146.60
Purchase #3	$149.95	10.864%	$166.2406	$166.24	$166.25	$166.20
Purchase #4	$232.40	12.413%	$261.2478	$261.25	$261.25	$261.20
Purchase #5	$200.28	10.844%	$221.9984	$222.00	$222.00	$222.00
Purchase #6	$118.35	4.312%	$123.4533	$123.45	$123.45	$123.50
Purchase #7	$145.72	13.376%	$165.2115	$165.21	$165.20	$165.20
7 purchase totals =	$1,101.44		$1,211.3161	$1,211.32	$1,211.30	$1,211.30