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	$243.63	3.334%	$251.7526	$251.75	$251.75	$251.80
Purchase #2	$90.38	11.180%	$100.4845	$100.48	$100.50	$100.50
Purchase #3	$62.79	3.815%	$65.1854	$65.19	$65.20	$65.20
Purchase #4	$187.49	12.865%	$211.6106	$211.61	$211.60	$211.60
Purchase #5	$59.62	13.380%	$67.5972	$67.60	$67.60	$67.60
Purchase #6	$82.78	11.539%	$92.332	$92.33	$92.35	$92.30
Purchase #7	$202.41	5.200%	$212.9353	$212.94	$212.95	$212.90
7 purchase totals =	$929.10		$1,001.8976	$1,001.90	$1,001.95	$1,001.90