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	$156.65	7.628%	$168.5993	$168.60	$168.60	$168.60
Purchase #2	$94.43	13.234%	$106.9269	$106.93	$106.95	$106.90
Purchase #3	$94.99	13.707%	$108.0103	$108.01	$108.00	$108.00
Purchase #4	$53.69	3.506%	$55.5724	$55.57	$55.55	$55.60
Purchase #5	$45.52	12.149%	$51.0502	$51.05	$51.05	$51.10
Purchase #6	$86.95	3.342%	$89.8559	$89.86	$89.85	$89.90
Purchase #7	$167.91	8.619%	$182.3822	$182.38	$182.40	$182.40
7 purchase totals =	$700.14		$762.3972	$762.40	$762.40	$762.50