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	$147.69	3.694%	$153.1457	$153.15	$153.15	$153.10
Purchase #2	$171.29	5.709%	$181.0689	$181.07	$181.05	$181.10
Purchase #3	$213.73	8.620%	$232.1535	$232.15	$232.15	$232.20
Purchase #4	$175.56	6.285%	$186.5939	$186.59	$186.60	$186.60
Purchase #5	$196.76	10.784%	$217.9786	$217.98	$218.00	$218.00
Purchase #6	$189.76	13.545%	$215.463	$215.46	$215.45	$215.50
Purchase #7	$106.72	4.767%	$111.8073	$111.81	$111.80	$111.80
7 purchase totals =	$1,201.51		$1,298.2109	$1,298.21	$1,298.20	$1,298.30