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	$93.79	4.798%	$98.29	$98.29	$98.30	$98.30
Purchase #2	$23.54	3.731%	$24.4183	$24.42	$24.40	$24.40
Purchase #3	$167.86	4.152%	$174.8295	$174.83	$174.85	$174.80
Purchase #4	$69.39	4.478%	$72.4973	$72.50	$72.50	$72.50
Purchase #5	$226.32	5.840%	$239.5371	$239.54	$239.55	$239.50
Purchase #6	$54.31	5.531%	$57.3139	$57.31	$57.30	$57.30
Purchase #7	$35.36	9.503%	$38.7203	$38.72	$38.70	$38.70
7 purchase totals =	$670.57		$705.6064	$705.61	$705.60	$705.50