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	$114.29	11.106%	$126.983	$126.98	$127.00	$127.00
Purchase #2	$58.55	6.685%	$62.4641	$62.46	$62.45	$62.50
Purchase #3	$226.54	4.564%	$236.8793	$236.88	$236.90	$236.90
Purchase #4	$98.91	9.615%	$108.4202	$108.42	$108.40	$108.40
Purchase #5	$195.86	13.626%	$222.5479	$222.55	$222.55	$222.50
Purchase #6	$28.56	13.576%	$32.4373	$32.44	$32.45	$32.40
Purchase #7	$200.99	9.321%	$219.7243	$219.72	$219.70	$219.70
7 purchase totals =	$923.70		$1,009.4561	$1,009.45	$1,009.45	$1,009.40