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	$119.82	3.696%	$124.2485	$124.25	$124.25	$124.20
Purchase #2	$87.76	7.175%	$94.0568	$94.06	$94.05	$94.10
Purchase #3	$225.69	13.806%	$256.8488	$256.85	$256.85	$256.80
Purchase #4	$166.30	10.587%	$183.9062	$183.91	$183.90	$183.90
Purchase #5	$224.81	10.642%	$248.7343	$248.73	$248.75	$248.70
Purchase #6	$143.45	5.579%	$151.4531	$151.45	$151.45	$151.50
Purchase #7	$59.48	13.168%	$67.3123	$67.31	$67.30	$67.30
7 purchase totals =	$1,027.31		$1,126.5600	$1,126.56	$1,126.55	$1,126.50