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	$95.53	6.318%	$101.5656	$101.57	$101.55	$101.60
Purchase #2	$50.27	7.615%	$54.0981	$54.10	$54.10	$54.10
Purchase #3	$180.31	6.741%	$192.4647	$192.46	$192.45	$192.50
Purchase #4	$106.39	6.139%	$112.9213	$112.92	$112.90	$112.90
Purchase #5	$48.54	12.637%	$54.674	$54.67	$54.65	$54.70
Purchase #6	$217.31	9.410%	$237.7589	$237.76	$237.75	$237.80
Purchase #7	$142.48	6.346%	$151.5218	$151.52	$151.50	$151.50
7 purchase totals =	$840.83		$905.0044	$905.00	$904.90	$905.10