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	$213.97	12.833%	$241.4288	$241.43	$241.45	$241.40
Purchase #2	$223.36	7.250%	$239.5536	$239.55	$239.55	$239.60
Purchase #3	$153.58	4.737%	$160.8551	$160.86	$160.85	$160.90
Purchase #4	$76.82	11.433%	$85.6028	$85.60	$85.60	$85.60
Purchase #5	$96.42	3.425%	$99.7224	$99.72	$99.70	$99.70
Purchase #6	$188.31	9.868%	$206.8924	$206.89	$206.90	$206.90
Purchase #7	$118.96	13.322%	$134.8079	$134.81	$134.80	$134.80
7 purchase totals =	$1,071.42		$1,168.8630	$1,168.86	$1,168.85	$1,168.90