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	$68.92	5.572%	$72.7602	$72.76	$72.75	$72.80
Purchase #2	$212.26	6.367%	$225.7746	$225.77	$225.75	$225.80
Purchase #3	$113.69	3.863%	$118.0818	$118.08	$118.10	$118.10
Purchase #4	$104.47	5.810%	$110.5397	$110.54	$110.55	$110.50
Purchase #5	$100.60	4.213%	$104.8383	$104.84	$104.85	$104.80
Purchase #6	$247.59	4.753%	$259.358	$259.36	$259.35	$259.40
Purchase #7	$80.48	6.333%	$85.5768	$85.58	$85.60	$85.60
7 purchase totals =	$928.01		$976.9294	$976.93	$976.95	$977.00