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	$77.79	10.533%	$85.9836	$85.98	$86.00	$86.00
Purchase #2	$210.75	9.626%	$231.0368	$231.04	$231.05	$231.00
Purchase #3	$89.43	3.421%	$92.4894	$92.49	$92.50	$92.50
Purchase #4	$183.89	9.241%	$200.8833	$200.88	$200.90	$200.90
Purchase #5	$78.32	12.827%	$88.3661	$88.37	$88.35	$88.40
Purchase #6	$43.70	7.200%	$46.8464	$46.85	$46.85	$46.80
Purchase #7	$247.33	10.650%	$273.6706	$273.67	$273.65	$273.70
7 purchase totals =	$931.21		$1,019.2762	$1,019.28	$1,019.30	$1,019.30