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	$84.95	10.644%	$93.9921	$93.99	$94.00	$94.00
Purchase #2	$75.72	4.175%	$78.8813	$78.88	$78.90	$78.90
Purchase #3	$180.85	10.374%	$199.6114	$199.61	$199.60	$199.60
Purchase #4	$231.69	7.535%	$249.1478	$249.15	$249.15	$249.10
Purchase #5	$211.32	5.190%	$222.2875	$222.29	$222.30	$222.30
Purchase #6	$47.87	8.374%	$51.8786	$51.88	$51.90	$51.90
Purchase #7	$199.64	4.487%	$208.5978	$208.60	$208.60	$208.60
7 purchase totals =	$1,032.04		$1,104.3965	$1,104.40	$1,104.45	$1,104.40