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	$41.42	12.110%	$46.436	$46.44	$46.45	$46.40
Purchase #2	$13.81	7.622%	$14.8626	$14.86	$14.85	$14.90
Purchase #3	$77.29	6.653%	$82.4321	$82.43	$82.45	$82.40
Purchase #4	$248.43	6.472%	$264.5084	$264.51	$264.50	$264.50
Purchase #5	$206.61	12.577%	$232.5953	$232.60	$232.60	$232.60
Purchase #6	$82.87	3.680%	$85.9196	$85.92	$85.90	$85.90
Purchase #7	$211.78	7.681%	$228.0468	$228.05	$228.05	$228.00
7 purchase totals =	$882.21		$954.8008	$954.81	$954.80	$954.70