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	$177.63	13.299%	$201.253	$201.25	$201.25	$201.30
Purchase #2	$39.26	9.300%	$42.9112	$42.91	$42.90	$42.90
Purchase #3	$227.61	5.661%	$240.495	$240.50	$240.50	$240.50
Purchase #4	$81.88	6.315%	$87.0507	$87.05	$87.05	$87.10
Purchase #5	$151.28	13.102%	$171.1007	$171.10	$171.10	$171.10
Purchase #6	$31.31	13.376%	$35.498	$35.50	$35.50	$35.50
Purchase #7	$241.26	11.562%	$269.1545	$269.15	$269.15	$269.20
7 purchase totals =	$950.23		$1,047.4631	$1,047.46	$1,047.45	$1,047.60