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	$194.37	11.663%	$217.0394	$217.04	$217.05	$217.00
Purchase #2	$12.68	6.253%	$13.4729	$13.47	$13.45	$13.50
Purchase #3	$152.25	7.728%	$164.0159	$164.02	$164.00	$164.00
Purchase #4	$79.89	13.614%	$90.7662	$90.77	$90.75	$90.80
Purchase #5	$92.38	6.193%	$98.1011	$98.10	$98.10	$98.10
Purchase #6	$106.92	11.411%	$119.1206	$119.12	$119.10	$119.10
Purchase #7	$166.57	7.576%	$179.1893	$179.19	$179.20	$179.20
7 purchase totals =	$805.06		$881.7054	$881.71	$881.65	$881.70