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	$148.32	6.680%	$158.2278	$158.23	$158.25	$158.20
Purchase #2	$26.44	12.272%	$29.6847	$29.68	$29.70	$29.70
Purchase #3	$85.69	12.503%	$96.4038	$96.40	$96.40	$96.40
Purchase #4	$83.54	7.485%	$89.793	$89.79	$89.80	$89.80
Purchase #5	$117.63	4.835%	$123.3174	$123.32	$123.30	$123.30
Purchase #6	$51.63	7.267%	$55.382	$55.38	$55.40	$55.40
Purchase #7	$206.76	10.619%	$228.7158	$228.72	$228.70	$228.70
7 purchase totals =	$720.01		$781.5245	$781.52	$781.55	$781.50