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	$181.31	13.270%	$205.3698	$205.37	$205.35	$205.40
Purchase #2	$243.72	4.683%	$255.1334	$255.13	$255.15	$255.10
Purchase #3	$49.31	5.480%	$52.0122	$52.01	$52.00	$52.00
Purchase #4	$225.51	13.150%	$255.1646	$255.16	$255.15	$255.20
Purchase #5	$101.93	4.393%	$106.4078	$106.41	$106.40	$106.40
Purchase #6	$206.34	4.758%	$216.1577	$216.16	$216.15	$216.20
Purchase #7	$152.79	3.262%	$157.774	$157.77	$157.75	$157.80
7 purchase totals =	$1,160.91		$1,248.0195	$1,248.01	$1,247.95	$1,248.10