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	$116.83	10.119%	$128.652	$128.65	$128.65	$128.70
Purchase #2	$200.76	11.445%	$223.737	$223.74	$223.75	$223.70
Purchase #3	$7.33	10.836%	$8.1243	$8.12	$8.10	$8.10
Purchase #4	$158.54	13.617%	$180.1284	$180.13	$180.15	$180.10
Purchase #5	$226.39	7.139%	$242.552	$242.55	$242.55	$242.60
Purchase #6	$153.30	8.706%	$166.6463	$166.65	$166.65	$166.60
Purchase #7	$69.48	13.355%	$78.7591	$78.76	$78.75	$78.80
7 purchase totals =	$932.63		$1,028.5991	$1,028.60	$1,028.60	$1,028.60