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	$182.55	4.110%	$190.0528	$190.05	$190.05	$190.10
Purchase #2	$57.78	3.189%	$59.6226	$59.62	$59.60	$59.60
Purchase #3	$26.84	3.111%	$27.675	$27.68	$27.70	$27.70
Purchase #4	$214.57	5.183%	$225.6912	$225.69	$225.70	$225.70
Purchase #5	$175.29	6.866%	$187.3254	$187.33	$187.35	$187.30
Purchase #6	$200.81	5.383%	$211.6196	$211.62	$211.60	$211.60
Purchase #7	$139.92	8.861%	$152.3183	$152.32	$152.30	$152.30
7 purchase totals =	$997.76		$1,054.3049	$1,054.31	$1,054.30	$1,054.30