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	$176.25	7.539%	$189.5375	$189.54	$189.55	$189.50
Purchase #2	$138.89	9.175%	$151.6332	$151.63	$151.65	$151.60
Purchase #3	$13.37	8.502%	$14.5067	$14.51	$14.50	$14.50
Purchase #4	$94.45	6.575%	$100.6601	$100.66	$100.65	$100.70
Purchase #5	$147.85	6.144%	$156.9339	$156.93	$156.95	$156.90
Purchase #6	$210.30	13.322%	$238.3162	$238.32	$238.30	$238.30
Purchase #7	$197.81	6.436%	$210.5411	$210.54	$210.55	$210.50
7 purchase totals =	$978.92		$1,062.1287	$1,062.13	$1,062.15	$1,062.00