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	$164.33	10.239%	$181.1557	$181.16	$181.15	$181.20
Purchase #2	$142.85	6.309%	$151.8624	$151.86	$151.85	$151.90
Purchase #3	$34.60	9.685%	$37.951	$37.95	$37.95	$38.00
Purchase #4	$140.66	8.323%	$152.3671	$152.37	$152.35	$152.40
Purchase #5	$219.81	13.113%	$248.6337	$248.63	$248.65	$248.60
Purchase #6	$53.38	11.863%	$59.7125	$59.71	$59.70	$59.70
Purchase #7	$164.84	9.389%	$180.3168	$180.32	$180.30	$180.30
7 purchase totals =	$920.47		$1,011.9992	$1,012.00	$1,011.95	$1,012.10