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	$171.26	3.307%	$176.9236	$176.92	$176.90	$176.90
Purchase #2	$12.72	6.220%	$13.5112	$13.51	$13.50	$13.50
Purchase #3	$176.82	4.636%	$185.0174	$185.02	$185.00	$185.00
Purchase #4	$158.38	4.258%	$165.1238	$165.12	$165.10	$165.10
Purchase #5	$31.52	11.345%	$35.0959	$35.10	$35.10	$35.10
Purchase #6	$161.50	7.694%	$173.9258	$173.93	$173.95	$173.90
Purchase #7	$188.46	3.356%	$194.7847	$194.78	$194.80	$194.80
7 purchase totals =	$900.66		$944.3824	$944.38	$944.35	$944.30