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	$185.53	7.695%	$199.8065	$199.81	$199.80	$199.80
Purchase #2	$153.78	4.364%	$160.491	$160.49	$160.50	$160.50
Purchase #3	$227.46	10.597%	$251.5639	$251.56	$251.55	$251.60
Purchase #4	$12.56	5.765%	$13.2841	$13.28	$13.30	$13.30
Purchase #5	$147.96	11.151%	$164.459	$164.46	$164.45	$164.50
Purchase #6	$130.76	12.867%	$147.5849	$147.58	$147.60	$147.60
Purchase #7	$237.45	10.442%	$262.2445	$262.24	$262.25	$262.20
7 purchase totals =	$1,095.50		$1,199.4339	$1,199.42	$1,199.45	$1,199.50