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	$212.68	11.170%	$236.4364	$236.44	$236.45	$236.40
Purchase #2	$231.98	4.432%	$242.2614	$242.26	$242.25	$242.30
Purchase #3	$227.86	5.432%	$240.2374	$240.24	$240.25	$240.20
Purchase #4	$15.53	12.678%	$17.4989	$17.50	$17.50	$17.50
Purchase #5	$70.38	11.217%	$78.2745	$78.27	$78.25	$78.30
Purchase #6	$169.64	13.578%	$192.6737	$192.67	$192.65	$192.70
Purchase #7	$76.54	3.127%	$78.9334	$78.93	$78.95	$78.90
7 purchase totals =	$1,004.61		$1,086.3157	$1,086.31	$1,086.30	$1,086.30