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	$237.66	6.793%	$253.8042	$253.80	$253.80	$253.80
Purchase #2	$21.29	13.847%	$24.238	$24.24	$24.25	$24.20
Purchase #3	$167.94	11.693%	$187.5772	$187.58	$187.60	$187.60
Purchase #4	$190.55	4.113%	$198.3873	$198.39	$198.40	$198.40
Purchase #5	$53.91	6.448%	$57.3861	$57.39	$57.40	$57.40
Purchase #6	$179.44	5.564%	$189.424	$189.42	$189.40	$189.40
Purchase #7	$227.89	10.369%	$251.5199	$251.52	$251.50	$251.50
7 purchase totals =	$1,078.68		$1,162.3367	$1,162.34	$1,162.35	$1,162.30