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	$219.71	11.762%	$245.5523	$245.55	$245.55	$245.60
Purchase #2	$59.48	8.443%	$64.5019	$64.50	$64.50	$64.50
Purchase #3	$127.46	9.437%	$139.4884	$139.49	$139.50	$139.50
Purchase #4	$238.84	6.607%	$254.6202	$254.62	$254.60	$254.60
Purchase #5	$83.36	6.704%	$88.9485	$88.95	$88.95	$88.90
Purchase #6	$124.32	7.361%	$133.4712	$133.47	$133.45	$133.50
Purchase #7	$200.65	4.591%	$209.8618	$209.86	$209.85	$209.90
7 purchase totals =	$1,053.82		$1,136.4443	$1,136.44	$1,136.40	$1,136.50