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	$104.45	6.870%	$111.6257	$111.63	$111.65	$111.60
Purchase #2	$229.76	10.384%	$253.6183	$253.62	$253.60	$253.60
Purchase #3	$154.90	7.414%	$166.3843	$166.38	$166.40	$166.40
Purchase #4	$20.86	10.308%	$23.0102	$23.01	$23.00	$23.00
Purchase #5	$201.59	7.481%	$216.6709	$216.67	$216.65	$216.70
Purchase #6	$214.42	3.798%	$222.5637	$222.56	$222.55	$222.60
Purchase #7	$182.43	12.454%	$205.1498	$205.15	$205.15	$205.10
7 purchase totals =	$1,108.41		$1,199.0229	$1,199.02	$1,199.00	$1,199.00