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	$66.88	7.544%	$71.9254	$71.93	$71.95	$71.90
Purchase #2	$92.25	8.413%	$100.011	$100.01	$100.00	$100.00
Purchase #3	$169.51	13.248%	$191.9667	$191.97	$191.95	$192.00
Purchase #4	$59.85	8.423%	$64.8912	$64.89	$64.90	$64.90
Purchase #5	$225.36	8.645%	$244.8424	$244.84	$244.85	$244.80
Purchase #6	$127.98	8.490%	$138.8455	$138.85	$138.85	$138.80
Purchase #7	$177.69	8.289%	$192.4187	$192.42	$192.40	$192.40
7 purchase totals =	$919.52		$1,004.9009	$1,004.91	$1,004.90	$1,004.80