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	$195.77	9.165%	$213.7123	$213.71	$213.70	$213.70
Purchase #2	$104.72	13.126%	$118.4655	$118.47	$118.45	$118.50
Purchase #3	$81.98	11.403%	$91.3282	$91.33	$91.35	$91.30
Purchase #4	$145.85	11.376%	$162.4419	$162.44	$162.45	$162.40
Purchase #5	$70.89	10.380%	$78.2484	$78.25	$78.25	$78.20
Purchase #6	$231.98	5.431%	$244.5788	$244.58	$244.60	$244.60
Purchase #7	$234.77	11.271%	$261.2309	$261.23	$261.25	$261.20
7 purchase totals =	$1,065.96		$1,170.0060	$1,170.01	$1,170.05	$1,169.90