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	$191.41	8.787%	$208.2292	$208.23	$208.25	$208.20
Purchase #2	$63.57	6.229%	$67.5298	$67.53	$67.55	$67.50
Purchase #3	$185.64	3.169%	$191.5229	$191.52	$191.50	$191.50
Purchase #4	$12.76	8.268%	$13.815	$13.82	$13.80	$13.80
Purchase #5	$218.58	4.714%	$228.8839	$228.88	$228.90	$228.90
Purchase #6	$137.32	3.606%	$142.2718	$142.27	$142.25	$142.30
Purchase #7	$249.33	4.200%	$259.8019	$259.80	$259.80	$259.80
7 purchase totals =	$1,058.61		$1,112.0545	$1,112.05	$1,112.05	$1,112.00