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	$195.26	11.550%	$217.8125	$217.81	$217.80	$217.80
Purchase #2	$54.77	4.527%	$57.2494	$57.25	$57.25	$57.20
Purchase #3	$200.71	13.788%	$228.3839	$228.38	$228.40	$228.40
Purchase #4	$185.50	5.815%	$196.2868	$196.29	$196.30	$196.30
Purchase #5	$210.76	4.188%	$219.5866	$219.59	$219.60	$219.60
Purchase #6	$26.69	7.483%	$28.6872	$28.69	$28.70	$28.70
Purchase #7	$198.41	10.422%	$219.0883	$219.09	$219.10	$219.10
7 purchase totals =	$1,072.10		$1,167.0947	$1,167.10	$1,167.15	$1,167.10