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	$175.77	9.590%	$192.6263	$192.63	$192.65	$192.60
Purchase #2	$103.43	8.564%	$112.2877	$112.29	$112.30	$112.30
Purchase #3	$170.48	8.646%	$185.2197	$185.22	$185.20	$185.20
Purchase #4	$158.56	4.565%	$165.7983	$165.80	$165.80	$165.80
Purchase #5	$112.89	4.549%	$118.0254	$118.03	$118.05	$118.00
Purchase #6	$10.95	4.595%	$11.4532	$11.45	$11.45	$11.50
Purchase #7	$183.96	3.577%	$190.5402	$190.54	$190.55	$190.50
7 purchase totals =	$916.04		$975.9508	$975.96	$976.00	$975.90