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	$44.29	3.312%	$45.7569	$45.76	$45.75	$45.80
Purchase #2	$180.58	8.820%	$196.5072	$196.51	$196.50	$196.50
Purchase #3	$78.82	11.112%	$87.5785	$87.58	$87.60	$87.60
Purchase #4	$166.77	11.699%	$186.2804	$186.28	$186.30	$186.30
Purchase #5	$101.50	7.330%	$108.94	$108.94	$108.95	$108.90
Purchase #6	$228.97	9.462%	$250.6351	$250.64	$250.65	$250.60
Purchase #7	$156.79	8.635%	$170.3288	$170.33	$170.35	$170.30
7 purchase totals =	$957.72		$1,046.0269	$1,046.04	$1,046.10	$1,046.00