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	$192.48	4.222%	$200.6065	$200.61	$200.60	$200.60
Purchase #2	$190.30	4.757%	$199.3526	$199.35	$199.35	$199.40
Purchase #3	$165.77	7.487%	$178.1812	$178.18	$178.20	$178.20
Purchase #4	$122.39	7.681%	$131.7908	$131.79	$131.80	$131.80
Purchase #5	$77.71	7.394%	$83.4559	$83.46	$83.45	$83.50
Purchase #6	$106.58	11.248%	$118.5681	$118.57	$118.55	$118.60
Purchase #7	$133.82	10.850%	$148.3395	$148.34	$148.35	$148.30
7 purchase totals =	$989.05		$1,060.2946	$1,060.30	$1,060.30	$1,060.40