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	$65.28	3.153%	$67.3383	$67.34	$67.35	$67.30
Purchase #2	$78.31	9.434%	$85.6978	$85.70	$85.70	$85.70
Purchase #3	$247.43	11.772%	$276.5575	$276.56	$276.55	$276.60
Purchase #4	$214.29	7.612%	$230.6018	$230.60	$230.60	$230.60
Purchase #5	$72.78	12.371%	$81.7836	$81.78	$81.80	$81.80
Purchase #6	$184.73	6.354%	$196.4677	$196.47	$196.45	$196.50
Purchase #7	$146.40	6.190%	$155.4622	$155.46	$155.45	$155.50
7 purchase totals =	$1,009.22		$1,093.9089	$1,093.91	$1,093.90	$1,094.00