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	$102.74	6.717%	$109.641	$109.64	$109.65	$109.60
Purchase #2	$140.73	5.558%	$148.5518	$148.55	$148.55	$148.60
Purchase #3	$174.44	13.772%	$198.4639	$198.46	$198.45	$198.50
Purchase #4	$81.83	11.629%	$91.346	$91.35	$91.35	$91.30
Purchase #5	$203.70	6.396%	$216.7287	$216.73	$216.75	$216.70
Purchase #6	$89.56	10.382%	$98.8581	$98.86	$98.85	$98.90
Purchase #7	$156.71	7.798%	$168.9302	$168.93	$168.95	$168.90
7 purchase totals =	$949.71		$1,032.5197	$1,032.52	$1,032.55	$1,032.50