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	$212.77	5.778%	$225.0639	$225.06	$225.05	$225.10
Purchase #2	$159.58	5.431%	$168.2468	$168.25	$168.25	$168.20
Purchase #3	$145.40	3.475%	$150.4527	$150.45	$150.45	$150.50
Purchase #4	$62.46	6.632%	$66.6023	$66.60	$66.60	$66.60
Purchase #5	$227.27	10.465%	$251.0538	$251.05	$251.05	$251.10
Purchase #6	$58.32	11.333%	$64.9294	$64.93	$64.95	$64.90
Purchase #7	$221.81	9.578%	$243.055	$243.06	$243.05	$243.10
7 purchase totals =	$1,087.61		$1,169.4039	$1,169.40	$1,169.40	$1,169.50