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	$153.60	9.800%	$168.6528	$168.65	$168.65	$168.70
Purchase #2	$122.75	7.355%	$131.7783	$131.78	$131.80	$131.80
Purchase #3	$67.39	8.764%	$73.2961	$73.30	$73.30	$73.30
Purchase #4	$163.78	5.821%	$173.3136	$173.31	$173.30	$173.30
Purchase #5	$74.99	9.398%	$82.0376	$82.04	$82.05	$82.00
Purchase #6	$191.55	4.569%	$200.3019	$200.30	$200.30	$200.30
Purchase #7	$227.76	5.438%	$240.1456	$240.15	$240.15	$240.10
7 purchase totals =	$1,001.82		$1,069.5259	$1,069.53	$1,069.55	$1,069.50