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	$84.82	11.570%	$94.6337	$94.63	$94.65	$94.60
Purchase #2	$64.81	11.804%	$72.4602	$72.46	$72.45	$72.50
Purchase #3	$83.93	3.110%	$86.5402	$86.54	$86.55	$86.50
Purchase #4	$196.74	6.799%	$210.1164	$210.12	$210.10	$210.10
Purchase #5	$177.38	6.408%	$188.7465	$188.75	$188.75	$188.70
Purchase #6	$184.52	13.138%	$208.7622	$208.76	$208.75	$208.80
Purchase #7	$160.93	12.158%	$180.4959	$180.50	$180.50	$180.50
7 purchase totals =	$953.13		$1,041.7551	$1,041.76	$1,041.75	$1,041.70