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	$190.71	8.486%	$206.8937	$206.89	$206.90	$206.90
Purchase #2	$195.98	12.649%	$220.7695	$220.77	$220.75	$220.80
Purchase #3	$165.43	12.158%	$185.543	$185.54	$185.55	$185.50
Purchase #4	$157.61	8.863%	$171.579	$171.58	$171.60	$171.60
Purchase #5	$99.37	4.667%	$104.0076	$104.01	$104.00	$104.00
Purchase #6	$10.39	9.533%	$11.3805	$11.38	$11.40	$11.40
Purchase #7	$186.50	5.561%	$196.8713	$196.87	$196.85	$196.90
7 purchase totals =	$1,005.99		$1,097.0446	$1,097.04	$1,097.05	$1,097.10