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	$112.82	5.811%	$119.376	$119.38	$119.40	$119.40
Purchase #2	$201.93	7.260%	$216.5901	$216.59	$216.60	$216.60
Purchase #3	$74.26	6.297%	$78.9362	$78.94	$78.95	$78.90
Purchase #4	$111.33	10.796%	$123.3492	$123.35	$123.35	$123.30
Purchase #5	$189.81	13.427%	$215.2958	$215.30	$215.30	$215.30
Purchase #6	$175.63	3.850%	$182.3918	$182.39	$182.40	$182.40
Purchase #7	$153.40	10.358%	$169.2892	$169.29	$169.30	$169.30
7 purchase totals =	$1,019.18		$1,105.2283	$1,105.24	$1,105.30	$1,105.20