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	$164.50	11.218%	$182.9536	$182.95	$182.95	$183.00
Purchase #2	$108.26	3.325%	$111.8596	$111.86	$111.85	$111.90
Purchase #3	$187.87	4.543%	$196.4049	$196.40	$196.40	$196.40
Purchase #4	$196.68	10.277%	$216.8928	$216.89	$216.90	$216.90
Purchase #5	$169.58	6.207%	$180.1058	$180.11	$180.10	$180.10
Purchase #6	$165.55	8.753%	$180.0406	$180.04	$180.05	$180.00
Purchase #7	$83.90	9.734%	$92.0668	$92.07	$92.05	$92.10
7 purchase totals =	$1,076.34		$1,160.3241	$1,160.32	$1,160.30	$1,160.40