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	$82.35	4.288%	$85.8812	$85.88	$85.90	$85.90
Purchase #2	$139.88	4.452%	$146.1075	$146.11	$146.10	$146.10
Purchase #3	$203.43	4.334%	$212.2467	$212.25	$212.25	$212.20
Purchase #4	$215.52	6.130%	$228.7314	$228.73	$228.75	$228.70
Purchase #5	$67.27	9.812%	$73.8705	$73.87	$73.85	$73.90
Purchase #6	$113.98	4.446%	$119.0476	$119.05	$119.05	$119.00
Purchase #7	$201.90	9.179%	$220.4324	$220.43	$220.45	$220.40
7 purchase totals =	$1,024.33		$1,086.3173	$1,086.32	$1,086.35	$1,086.20