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	$174.78	4.388%	$182.4493	$182.45	$182.45	$182.40
Purchase #2	$196.45	13.289%	$222.5562	$222.56	$222.55	$222.60
Purchase #3	$71.84	9.677%	$78.792	$78.79	$78.80	$78.80
Purchase #4	$5.47	13.129%	$6.1882	$6.19	$6.20	$6.20
Purchase #5	$34.56	10.421%	$38.1615	$38.16	$38.15	$38.20
Purchase #6	$211.33	11.759%	$236.1803	$236.18	$236.20	$236.20
Purchase #7	$38.86	8.465%	$42.1495	$42.15	$42.15	$42.10
7 purchase totals =	$733.29		$806.4770	$806.48	$806.50	$806.50