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	$166.60	4.800%	$174.5968	$174.60	$174.60	$174.60
Purchase #2	$183.70	7.200%	$196.9264	$196.93	$196.95	$196.90
Purchase #3	$90.69	11.472%	$101.094	$101.09	$101.10	$101.10
Purchase #4	$94.96	7.354%	$101.9434	$101.94	$101.95	$101.90
Purchase #5	$200.86	5.394%	$211.6944	$211.69	$211.70	$211.70
Purchase #6	$42.53	11.198%	$47.2925	$47.29	$47.30	$47.30
Purchase #7	$88.96	3.259%	$91.8592	$91.86	$91.85	$91.90
7 purchase totals =	$868.30		$925.4067	$925.40	$925.45	$925.40