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	$94.50	11.307%	$105.1851	$105.19	$105.20	$105.20
Purchase #2	$135.83	12.149%	$152.332	$152.33	$152.35	$152.30
Purchase #3	$108.88	10.854%	$120.6978	$120.70	$120.70	$120.70
Purchase #4	$196.59	9.225%	$214.7254	$214.73	$214.75	$214.70
Purchase #5	$137.76	9.426%	$150.7453	$150.75	$150.75	$150.70
Purchase #6	$143.73	5.121%	$151.0904	$151.09	$151.10	$151.10
Purchase #7	$168.43	7.655%	$181.3233	$181.32	$181.30	$181.30
7 purchase totals =	$985.72		$1,076.0993	$1,076.11	$1,076.15	$1,076.00