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	$94.69	12.442%	$106.4713	$106.47	$106.45	$106.50
Purchase #2	$132.64	3.637%	$137.4641	$137.46	$137.45	$137.50
Purchase #3	$95.68	12.230%	$107.3817	$107.38	$107.40	$107.40
Purchase #4	$155.54	10.644%	$172.0957	$172.10	$172.10	$172.10
Purchase #5	$67.37	9.275%	$73.6186	$73.62	$73.60	$73.60
Purchase #6	$215.82	3.382%	$223.119	$223.12	$223.10	$223.10
Purchase #7	$210.33	3.352%	$217.3803	$217.38	$217.40	$217.40
7 purchase totals =	$972.07		$1,037.5307	$1,037.53	$1,037.50	$1,037.60