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	$186.60	4.726%	$195.4187	$195.42	$195.40	$195.40
Purchase #2	$107.83	4.784%	$112.9886	$112.99	$113.00	$113.00
Purchase #3	$187.97	4.514%	$196.455	$196.46	$196.45	$196.50
Purchase #4	$232.86	7.110%	$249.4163	$249.42	$249.40	$249.40
Purchase #5	$38.83	8.751%	$42.228	$42.23	$42.25	$42.20
Purchase #6	$54.45	7.431%	$58.4962	$58.50	$58.50	$58.50
Purchase #7	$54.65	9.256%	$59.7084	$59.71	$59.70	$59.70
7 purchase totals =	$863.19		$914.7112	$914.73	$914.70	$914.70