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	$72.64	13.334%	$82.3258	$82.33	$82.35	$82.30
Purchase #2	$101.91	7.614%	$109.6694	$109.67	$109.65	$109.70
Purchase #3	$177.91	10.449%	$196.4998	$196.50	$196.50	$196.50
Purchase #4	$243.96	12.833%	$275.2674	$275.27	$275.25	$275.30
Purchase #5	$63.75	4.868%	$66.8534	$66.85	$66.85	$66.90
Purchase #6	$144.83	12.595%	$163.0713	$163.07	$163.05	$163.10
Purchase #7	$124.92	4.394%	$130.409	$130.41	$130.40	$130.40
7 purchase totals =	$929.92		$1,024.0961	$1,024.10	$1,024.05	$1,024.20