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	$196.95	6.571%	$209.8916	$209.89	$209.90	$209.90
Purchase #2	$38.58	13.735%	$43.879	$43.88	$43.90	$43.90
Purchase #3	$199.39	12.135%	$223.586	$223.59	$223.60	$223.60
Purchase #4	$119.72	11.193%	$133.1203	$133.12	$133.10	$133.10
Purchase #5	$248.46	12.122%	$278.5783	$278.58	$278.60	$278.60
Purchase #6	$93.71	12.486%	$105.4106	$105.41	$105.40	$105.40
Purchase #7	$17.60	6.671%	$18.7741	$18.77	$18.75	$18.80
7 purchase totals =	$914.41		$1,013.2399	$1,013.24	$1,013.25	$1,013.30