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	$218.99	7.520%	$235.458	$235.46	$235.45	$235.50
Purchase #2	$9.75	6.372%	$10.3713	$10.37	$10.35	$10.40
Purchase #3	$90.79	12.869%	$102.4738	$102.47	$102.45	$102.50
Purchase #4	$98.92	4.655%	$103.5247	$103.52	$103.50	$103.50
Purchase #5	$236.84	9.450%	$259.2214	$259.22	$259.20	$259.20
Purchase #6	$221.87	12.164%	$248.8583	$248.86	$248.85	$248.90
Purchase #7	$142.61	6.694%	$152.1563	$152.16	$152.15	$152.20
7 purchase totals =	$1,019.77		$1,112.0638	$1,112.06	$1,111.95	$1,112.20