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	$159.34	13.551%	$180.9322	$180.93	$180.95	$180.90
Purchase #2	$12.96	7.527%	$13.9355	$13.94	$13.95	$13.90
Purchase #3	$214.25	5.407%	$225.8345	$225.83	$225.85	$225.80
Purchase #4	$182.33	12.182%	$204.5414	$204.54	$204.55	$204.50
Purchase #5	$29.77	4.767%	$31.1891	$31.19	$31.20	$31.20
Purchase #6	$106.89	6.282%	$113.6048	$113.60	$113.60	$113.60
Purchase #7	$245.32	13.143%	$277.5624	$277.56	$277.55	$277.60
7 purchase totals =	$950.86		$1,047.5999	$1,047.59	$1,047.65	$1,047.50