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	$137.39	9.852%	$150.9257	$150.93	$150.95	$150.90
Purchase #2	$181.33	4.258%	$189.051	$189.05	$189.05	$189.10
Purchase #3	$189.97	3.467%	$196.5563	$196.56	$196.55	$196.60
Purchase #4	$96.76	12.448%	$108.8047	$108.80	$108.80	$108.80
Purchase #5	$230.25	7.737%	$248.0644	$248.06	$248.05	$248.10
Purchase #6	$140.38	11.590%	$156.65	$156.65	$156.65	$156.70
Purchase #7	$98.33	4.614%	$102.8669	$102.87	$102.85	$102.90
7 purchase totals =	$1,074.41		$1,152.9190	$1,152.92	$1,152.90	$1,153.10