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	$152.59	8.693%	$165.8546	$165.85	$165.85	$165.90
Purchase #2	$77.65	7.611%	$83.5599	$83.56	$83.55	$83.60
Purchase #3	$157.48	13.520%	$178.7713	$178.77	$178.75	$178.80
Purchase #4	$122.55	11.333%	$136.4386	$136.44	$136.45	$136.40
Purchase #5	$205.72	3.613%	$213.1527	$213.15	$213.15	$213.20
Purchase #6	$109.92	12.435%	$123.5886	$123.59	$123.60	$123.60
Purchase #7	$135.93	9.484%	$148.8216	$148.82	$148.80	$148.80
7 purchase totals =	$961.84		$1,050.1873	$1,050.18	$1,050.15	$1,050.30