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	$161.74	3.532%	$167.4527	$167.45	$167.45	$167.50
Purchase #2	$240.83	4.173%	$250.8798	$250.88	$250.90	$250.90
Purchase #3	$164.60	5.645%	$173.8917	$173.89	$173.90	$173.90
Purchase #4	$83.85	3.394%	$86.6959	$86.70	$86.70	$86.70
Purchase #5	$160.50	6.701%	$171.2551	$171.26	$171.25	$171.30
Purchase #6	$62.43	3.381%	$64.5408	$64.54	$64.55	$64.50
Purchase #7	$48.76	9.375%	$53.3313	$53.33	$53.35	$53.30
7 purchase totals =	$922.71		$968.0473	$968.05	$968.10	$968.10