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	$162.56	10.402%	$179.4695	$179.47	$179.45	$179.50
Purchase #2	$206.37	8.449%	$223.8062	$223.81	$223.80	$223.80
Purchase #3	$56.43	8.770%	$61.3789	$61.38	$61.40	$61.40
Purchase #4	$168.39	13.285%	$190.7606	$190.76	$190.75	$190.80
Purchase #5	$93.54	13.532%	$106.1978	$106.20	$106.20	$106.20
Purchase #6	$159.61	9.237%	$174.3532	$174.35	$174.35	$174.40
Purchase #7	$104.51	11.336%	$116.3573	$116.36	$116.35	$116.40
7 purchase totals =	$951.41		$1,052.3235	$1,052.33	$1,052.30	$1,052.50