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	$196.86	9.874%	$216.298	$216.30	$216.30	$216.30
Purchase #2	$25.46	5.243%	$26.7949	$26.79	$26.80	$26.80
Purchase #3	$52.47	12.813%	$59.193	$59.19	$59.20	$59.20
Purchase #4	$208.41	5.468%	$219.8059	$219.81	$219.80	$219.80
Purchase #5	$240.39	6.113%	$255.085	$255.09	$255.10	$255.10
Purchase #6	$104.27	5.221%	$109.7139	$109.71	$109.70	$109.70
Purchase #7	$236.44	8.632%	$256.8495	$256.85	$256.85	$256.80
7 purchase totals =	$1,064.30		$1,143.7402	$1,143.74	$1,143.75	$1,143.70