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	$236.33	7.372%	$253.7522	$253.75	$253.75	$253.80
Purchase #2	$26.32	4.758%	$27.5723	$27.57	$27.55	$27.60
Purchase #3	$135.27	12.274%	$151.873	$151.87	$151.85	$151.90
Purchase #4	$84.29	6.130%	$89.457	$89.46	$89.45	$89.50
Purchase #5	$117.83	6.860%	$125.9131	$125.91	$125.90	$125.90
Purchase #6	$192.39	8.384%	$208.52	$208.52	$208.50	$208.50
Purchase #7	$163.39	13.572%	$185.5653	$185.57	$185.55	$185.60
7 purchase totals =	$955.82		$1,042.6529	$1,042.65	$1,042.55	$1,042.80