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	$209.27	7.593%	$225.1599	$225.16	$225.15	$225.20
Purchase #2	$195.26	9.209%	$213.2415	$213.24	$213.25	$213.20
Purchase #3	$200.66	5.378%	$211.4515	$211.45	$211.45	$211.50
Purchase #4	$138.47	12.298%	$155.499	$155.50	$155.50	$155.50
Purchase #5	$51.38	6.172%	$54.5512	$54.55	$54.55	$54.60
Purchase #6	$101.99	9.199%	$111.3721	$111.37	$111.35	$111.40
Purchase #7	$48.89	11.273%	$54.4014	$54.40	$54.40	$54.40
7 purchase totals =	$945.92		$1,025.6766	$1,025.67	$1,025.65	$1,025.80