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	$140.59	7.652%	$151.3479	$151.35	$151.35	$151.30
Purchase #2	$32.86	12.612%	$37.0043	$37.00	$37.00	$37.00
Purchase #3	$79.65	5.287%	$83.8611	$83.86	$83.85	$83.90
Purchase #4	$122.42	12.400%	$137.6001	$137.60	$137.60	$137.60
Purchase #5	$95.60	12.262%	$107.3225	$107.32	$107.30	$107.30
Purchase #6	$91.44	5.438%	$96.4125	$96.41	$96.40	$96.40
Purchase #7	$136.49	12.465%	$153.5035	$153.50	$153.50	$153.50
7 purchase totals =	$699.05		$767.0519	$767.04	$767.00	$767.00