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	$73.28	3.819%	$76.0786	$76.08	$76.10	$76.10
Purchase #2	$168.81	3.769%	$175.1724	$175.17	$175.15	$175.20
Purchase #3	$117.47	11.787%	$131.3162	$131.32	$131.30	$131.30
Purchase #4	$55.88	11.836%	$62.494	$62.49	$62.50	$62.50
Purchase #5	$51.34	9.263%	$56.0956	$56.10	$56.10	$56.10
Purchase #6	$82.25	5.133%	$86.4719	$86.47	$86.45	$86.50
Purchase #7	$37.93	6.591%	$40.43	$40.43	$40.45	$40.40
7 purchase totals =	$586.96		$628.0587	$628.06	$628.05	$628.10