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	$169.68	9.530%	$185.8505	$185.85	$185.85	$185.90
Purchase #2	$170.57	9.592%	$186.9311	$186.93	$186.95	$186.90
Purchase #3	$132.88	6.469%	$141.476	$141.48	$141.50	$141.50
Purchase #4	$212.88	13.166%	$240.9078	$240.91	$240.90	$240.90
Purchase #5	$65.32	11.431%	$72.7867	$72.79	$72.80	$72.80
Purchase #6	$156.90	7.202%	$168.1999	$168.20	$168.20	$168.20
Purchase #7	$145.65	13.175%	$164.8394	$164.84	$164.85	$164.80
7 purchase totals =	$1,053.88		$1,160.9914	$1,161.00	$1,161.05	$1,161.00