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	$199.26	3.561%	$206.3556	$206.36	$206.35	$206.40
Purchase #2	$12.33	13.537%	$13.9991	$14.00	$14.00	$14.00
Purchase #3	$49.69	6.813%	$53.0754	$53.08	$53.10	$53.10
Purchase #4	$210.92	10.738%	$233.5686	$233.57	$233.55	$233.60
Purchase #5	$206.38	7.801%	$222.4797	$222.48	$222.50	$222.50
Purchase #6	$201.66	11.504%	$224.859	$224.86	$224.85	$224.90
Purchase #7	$43.83	9.772%	$48.1131	$48.11	$48.10	$48.10
7 purchase totals =	$924.07		$1,002.4505	$1,002.46	$1,002.45	$1,002.60