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	$200.96	4.453%	$209.9087	$209.91	$209.90	$209.90
Purchase #2	$250.26	3.115%	$258.0556	$258.06	$258.05	$258.10
Purchase #3	$28.76	12.163%	$32.2581	$32.26	$32.25	$32.30
Purchase #4	$58.33	6.186%	$61.9383	$61.94	$61.95	$61.90
Purchase #5	$40.89	4.206%	$42.6098	$42.61	$42.60	$42.60
Purchase #6	$60.70	7.567%	$65.2932	$65.29	$65.30	$65.30
Purchase #7	$93.54	4.675%	$97.913	$97.91	$97.90	$97.90
7 purchase totals =	$733.44		$767.9767	$767.98	$767.95	$768.00