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	$212.44	7.802%	$229.0146	$229.01	$229.00	$229.00
Purchase #2	$240.45	13.577%	$273.0959	$273.10	$273.10	$273.10
Purchase #3	$107.48	11.277%	$119.6005	$119.60	$119.60	$119.60
Purchase #4	$223.57	9.105%	$243.926	$243.93	$243.95	$243.90
Purchase #5	$98.58	5.506%	$104.0078	$104.01	$104.00	$104.00
Purchase #6	$38.91	4.391%	$40.6185	$40.62	$40.60	$40.60
Purchase #7	$54.83	7.740%	$59.0738	$59.07	$59.05	$59.10
7 purchase totals =	$976.26		$1,069.3371	$1,069.34	$1,069.30	$1,069.30