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	$151.68	11.610%	$169.29	$169.29	$169.30	$169.30
Purchase #2	$193.51	9.516%	$211.9244	$211.92	$211.90	$211.90
Purchase #3	$112.83	12.505%	$126.9394	$126.94	$126.95	$126.90
Purchase #4	$226.25	5.562%	$238.834	$238.83	$238.85	$238.80
Purchase #5	$84.78	9.463%	$92.8027	$92.80	$92.80	$92.80
Purchase #6	$152.80	12.250%	$171.518	$171.52	$171.50	$171.50
Purchase #7	$60.54	7.241%	$64.9237	$64.92	$64.90	$64.90
7 purchase totals =	$982.39		$1,076.2322	$1,076.22	$1,076.20	$1,076.10