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	$83.61	7.456%	$89.844	$89.84	$89.85	$89.80
Purchase #2	$190.97	9.324%	$208.776	$208.78	$208.80	$208.80
Purchase #3	$69.92	3.282%	$72.2148	$72.21	$72.20	$72.20
Purchase #4	$191.50	5.143%	$201.3488	$201.35	$201.35	$201.30
Purchase #5	$148.80	5.454%	$156.9156	$156.92	$156.90	$156.90
Purchase #6	$179.25	4.306%	$186.9685	$186.97	$186.95	$187.00
Purchase #7	$186.52	5.356%	$196.51	$196.51	$196.50	$196.50
7 purchase totals =	$1,050.57		$1,112.5777	$1,112.58	$1,112.55	$1,112.50