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	$216.61	5.465%	$228.4477	$228.45	$228.45	$228.40
Purchase #2	$51.96	13.266%	$58.853	$58.85	$58.85	$58.90
Purchase #3	$114.40	9.613%	$125.3973	$125.40	$125.40	$125.40
Purchase #4	$155.48	5.843%	$164.5647	$164.56	$164.55	$164.60
Purchase #5	$98.71	5.208%	$103.8508	$103.85	$103.85	$103.90
Purchase #6	$99.49	11.576%	$111.007	$111.01	$111.00	$111.00
Purchase #7	$241.52	13.265%	$273.5576	$273.56	$273.55	$273.60
7 purchase totals =	$978.17		$1,065.6781	$1,065.68	$1,065.65	$1,065.80