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	$207.73	5.165%	$218.4593	$218.46	$218.45	$218.50
Purchase #2	$196.72	13.540%	$223.3559	$223.36	$223.35	$223.40
Purchase #3	$150.82	7.383%	$161.955	$161.96	$161.95	$162.00
Purchase #4	$169.34	10.503%	$187.1258	$187.13	$187.15	$187.10
Purchase #5	$78.65	5.298%	$82.8169	$82.82	$82.80	$82.80
Purchase #6	$139.80	10.411%	$154.3546	$154.35	$154.35	$154.40
Purchase #7	$156.67	8.393%	$169.8193	$169.82	$169.80	$169.80
7 purchase totals =	$1,099.73		$1,197.8868	$1,197.90	$1,197.85	$1,198.00