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	$142.76	8.533%	$154.9417	$154.94	$154.95	$154.90
Purchase #2	$186.79	7.178%	$200.1978	$200.20	$200.20	$200.20
Purchase #3	$51.73	11.851%	$57.8605	$57.86	$57.85	$57.90
Purchase #4	$95.86	13.632%	$108.9276	$108.93	$108.95	$108.90
Purchase #5	$171.41	11.353%	$190.8702	$190.87	$190.85	$190.90
Purchase #6	$186.28	11.330%	$207.3855	$207.39	$207.40	$207.40
Purchase #7	$181.91	5.135%	$191.2511	$191.25	$191.25	$191.30
7 purchase totals =	$1,016.74		$1,111.4344	$1,111.44	$1,111.45	$1,111.50