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	$197.53	7.361%	$212.0702	$212.07	$212.05	$212.10
Purchase #2	$161.50	11.673%	$180.3519	$180.35	$180.35	$180.40
Purchase #3	$99.66	8.335%	$107.9667	$107.97	$107.95	$108.00
Purchase #4	$143.48	4.586%	$150.06	$150.06	$150.05	$150.10
Purchase #5	$98.27	11.643%	$109.7116	$109.71	$109.70	$109.70
Purchase #6	$183.79	9.165%	$200.6344	$200.63	$200.65	$200.60
Purchase #7	$178.77	6.371%	$190.1594	$190.16	$190.15	$190.20
7 purchase totals =	$1,063.00		$1,150.9542	$1,150.95	$1,150.90	$1,151.10