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	$146.54	3.339%	$151.433	$151.43	$151.45	$151.40
Purchase #2	$67.33	13.306%	$76.2889	$76.29	$76.30	$76.30
Purchase #3	$76.34	3.328%	$78.8806	$78.88	$78.90	$78.90
Purchase #4	$207.38	5.535%	$218.8585	$218.86	$218.85	$218.90
Purchase #5	$13.65	8.848%	$14.8578	$14.86	$14.85	$14.90
Purchase #6	$88.31	3.539%	$91.4353	$91.44	$91.45	$91.40
Purchase #7	$153.89	6.735%	$164.2545	$164.25	$164.25	$164.30
7 purchase totals =	$753.44		$796.0086	$796.01	$796.05	$796.10