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	$113.76	11.350%	$126.6718	$126.67	$126.65	$126.70
Purchase #2	$205.30	9.668%	$225.1484	$225.15	$225.15	$225.10
Purchase #3	$45.82	5.775%	$48.4661	$48.47	$48.45	$48.50
Purchase #4	$80.73	11.697%	$90.173	$90.17	$90.15	$90.20
Purchase #5	$146.63	6.759%	$156.5407	$156.54	$156.55	$156.50
Purchase #6	$87.88	4.182%	$91.5551	$91.56	$91.55	$91.60
Purchase #7	$197.58	12.614%	$222.5027	$222.50	$222.50	$222.50
7 purchase totals =	$877.70		$961.0578	$961.06	$961.00	$961.10