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	$162.80	4.240%	$169.7027	$169.70	$169.70	$169.70
Purchase #2	$173.52	13.322%	$196.6363	$196.64	$196.65	$196.60
Purchase #3	$92.83	11.315%	$103.3337	$103.33	$103.35	$103.30
Purchase #4	$66.88	9.607%	$73.3052	$73.31	$73.30	$73.30
Purchase #5	$167.62	4.184%	$174.6332	$174.63	$174.65	$174.60
Purchase #6	$80.81	4.563%	$84.4974	$84.50	$84.50	$84.50
Purchase #7	$211.64	5.589%	$223.4686	$223.47	$223.45	$223.50
7 purchase totals =	$956.10		$1,025.5771	$1,025.58	$1,025.60	$1,025.50