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	$157.76	10.321%	$174.0424	$174.04	$174.05	$174.00
Purchase #2	$97.43	7.642%	$104.8756	$104.88	$104.90	$104.90
Purchase #3	$71.82	9.255%	$78.4669	$78.47	$78.45	$78.50
Purchase #4	$232.44	11.397%	$258.9312	$258.93	$258.95	$258.90
Purchase #5	$38.57	6.468%	$41.0647	$41.06	$41.05	$41.10
Purchase #6	$249.52	4.308%	$260.2693	$260.27	$260.25	$260.30
Purchase #7	$209.53	3.505%	$216.874	$216.87	$216.85	$216.90
7 purchase totals =	$1,057.07		$1,134.5241	$1,134.52	$1,134.50	$1,134.60