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	$168.77	13.471%	$191.505	$191.51	$191.50	$191.50
Purchase #2	$186.60	13.470%	$211.735	$211.74	$211.75	$211.70
Purchase #3	$90.77	7.141%	$97.2519	$97.25	$97.25	$97.30
Purchase #4	$159.51	8.142%	$172.4973	$172.50	$172.50	$172.50
Purchase #5	$71.39	5.672%	$75.4392	$75.44	$75.45	$75.40
Purchase #6	$85.72	6.207%	$91.0406	$91.04	$91.05	$91.00
Purchase #7	$156.65	9.713%	$171.8654	$171.87	$171.85	$171.90
7 purchase totals =	$919.41		$1,011.3344	$1,011.35	$1,011.35	$1,011.30