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	$216.47	9.704%	$237.4762	$237.48	$237.50	$237.50
Purchase #2	$153.81	7.636%	$165.5549	$165.55	$165.55	$165.60
Purchase #3	$38.91	13.520%	$44.1706	$44.17	$44.15	$44.20
Purchase #4	$213.45	13.698%	$242.6884	$242.69	$242.70	$242.70
Purchase #5	$52.69	13.335%	$59.7162	$59.72	$59.70	$59.70
Purchase #6	$237.80	4.143%	$247.6521	$247.65	$247.65	$247.70
Purchase #7	$120.65	8.236%	$130.5867	$130.59	$130.60	$130.60
7 purchase totals =	$1,033.78		$1,127.8451	$1,127.85	$1,127.85	$1,128.00