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	$139.96	7.375%	$150.2821	$150.28	$150.30	$150.30
Purchase #2	$182.31	8.568%	$197.9303	$197.93	$197.95	$197.90
Purchase #3	$100.76	11.201%	$112.0461	$112.05	$112.05	$112.00
Purchase #4	$152.42	5.231%	$160.3931	$160.39	$160.40	$160.40
Purchase #5	$214.30	10.399%	$236.5851	$236.59	$236.60	$236.60
Purchase #6	$151.37	3.355%	$156.4485	$156.45	$156.45	$156.40
Purchase #7	$84.80	6.368%	$90.2001	$90.20	$90.20	$90.20
7 purchase totals =	$1,025.92		$1,103.8853	$1,103.89	$1,103.95	$1,103.80