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	$167.86	4.807%	$175.929	$175.93	$175.95	$175.90
Purchase #2	$191.72	9.535%	$210.0005	$210.00	$210.00	$210.00
Purchase #3	$55.90	3.327%	$57.7598	$57.76	$57.75	$57.80
Purchase #4	$70.50	10.809%	$78.1203	$78.12	$78.10	$78.10
Purchase #5	$219.50	10.639%	$242.8526	$242.85	$242.85	$242.90
Purchase #6	$226.90	3.341%	$234.4807	$234.48	$234.50	$234.50
Purchase #7	$190.50	3.372%	$196.9237	$196.92	$196.90	$196.90
7 purchase totals =	$1,122.88		$1,196.0666	$1,196.06	$1,196.05	$1,196.10