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	$182.29	5.291%	$191.935	$191.94	$191.95	$191.90
Purchase #2	$87.76	3.375%	$90.7219	$90.72	$90.70	$90.70
Purchase #3	$61.87	4.136%	$64.4289	$64.43	$64.45	$64.40
Purchase #4	$67.73	5.450%	$71.4213	$71.42	$71.40	$71.40
Purchase #5	$166.30	4.686%	$174.0928	$174.09	$174.10	$174.10
Purchase #6	$56.51	3.103%	$58.2635	$58.26	$58.25	$58.30
Purchase #7	$105.50	4.723%	$110.4828	$110.48	$110.50	$110.50
7 purchase totals =	$727.96		$761.3462	$761.34	$761.35	$761.30