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	$111.32	4.179%	$115.9721	$115.97	$115.95	$116.00
Purchase #2	$147.52	10.435%	$162.9137	$162.91	$162.90	$162.90
Purchase #3	$218.83	3.764%	$227.0668	$227.07	$227.05	$227.10
Purchase #4	$133.53	7.770%	$143.9053	$143.91	$143.90	$143.90
Purchase #5	$173.32	13.371%	$196.4946	$196.49	$196.50	$196.50
Purchase #6	$141.25	3.122%	$145.6598	$145.66	$145.65	$145.70
Purchase #7	$149.56	11.570%	$166.8641	$166.86	$166.85	$166.90
7 purchase totals =	$1,075.33		$1,158.8764	$1,158.87	$1,158.80	$1,159.00