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	$232.25	13.820%	$264.347	$264.35	$264.35	$264.30
Purchase #2	$184.38	12.275%	$207.0126	$207.01	$207.00	$207.00
Purchase #3	$173.64	3.313%	$179.3927	$179.39	$179.40	$179.40
Purchase #4	$212.48	4.761%	$222.5962	$222.60	$222.60	$222.60
Purchase #5	$176.45	3.577%	$182.7616	$182.76	$182.75	$182.80
Purchase #6	$41.29	3.398%	$42.693	$42.69	$42.70	$42.70
Purchase #7	$88.70	10.504%	$98.017	$98.02	$98.00	$98.00
7 purchase totals =	$1,109.19		$1,196.8201	$1,196.82	$1,196.80	$1,196.80