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	$196.28	6.262%	$208.5711	$208.57	$208.55	$208.60
Purchase #2	$171.26	10.344%	$188.9751	$188.98	$189.00	$189.00
Purchase #3	$157.86	6.752%	$168.5187	$168.52	$168.50	$168.50
Purchase #4	$248.64	6.201%	$264.0582	$264.06	$264.05	$264.10
Purchase #5	$181.35	3.733%	$188.1198	$188.12	$188.10	$188.10
Purchase #6	$200.49	13.443%	$227.4419	$227.44	$227.45	$227.40
Purchase #7	$152.81	9.130%	$166.7616	$166.76	$166.75	$166.80
7 purchase totals =	$1,308.69		$1,412.4464	$1,412.45	$1,412.40	$1,412.50