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	$215.66	9.204%	$235.5093	$235.51	$235.50	$235.50
Purchase #2	$165.45	9.467%	$181.1132	$181.11	$181.10	$181.10
Purchase #3	$55.82	6.784%	$59.6068	$59.61	$59.60	$59.60
Purchase #4	$16.47	3.270%	$17.0086	$17.01	$17.00	$17.00
Purchase #5	$182.29	3.447%	$188.5735	$188.57	$188.55	$188.60
Purchase #6	$94.63	9.767%	$103.8725	$103.87	$103.85	$103.90
Purchase #7	$238.85	12.848%	$269.5374	$269.54	$269.55	$269.50
7 purchase totals =	$969.17		$1,055.2213	$1,055.22	$1,055.15	$1,055.20