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	$222.32	6.612%	$237.0198	$237.02	$237.00	$237.00
Purchase #2	$32.32	4.773%	$33.8626	$33.86	$33.85	$33.90
Purchase #3	$196.36	13.872%	$223.5991	$223.60	$223.60	$223.60
Purchase #4	$93.88	9.121%	$102.4428	$102.44	$102.45	$102.40
Purchase #5	$146.40	10.610%	$161.933	$161.93	$161.95	$161.90
Purchase #6	$25.77	11.710%	$28.7877	$28.79	$28.80	$28.80
Purchase #7	$210.72	3.461%	$218.013	$218.01	$218.00	$218.00
7 purchase totals =	$927.77		$1,005.6580	$1,005.65	$1,005.65	$1,005.60