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	$201.79	4.600%	$211.0723	$211.07	$211.05	$211.10
Purchase #2	$181.55	4.157%	$189.097	$189.10	$189.10	$189.10
Purchase #3	$42.38	6.680%	$45.211	$45.21	$45.20	$45.20
Purchase #4	$179.98	5.609%	$190.0751	$190.08	$190.10	$190.10
Purchase #5	$55.43	6.517%	$59.0424	$59.04	$59.05	$59.00
Purchase #6	$65.48	9.803%	$71.899	$71.90	$71.90	$71.90
Purchase #7	$119.91	9.438%	$131.2271	$131.23	$131.25	$131.20
7 purchase totals =	$846.52		$897.6239	$897.63	$897.65	$897.60