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	$180.70	10.741%	$200.109	$200.11	$200.10	$200.10
Purchase #2	$88.52	12.813%	$99.8621	$99.86	$99.85	$99.90
Purchase #3	$130.67	10.575%	$144.4884	$144.49	$144.50	$144.50
Purchase #4	$179.67	6.435%	$191.2318	$191.23	$191.25	$191.20
Purchase #5	$225.25	8.603%	$244.6283	$244.63	$244.65	$244.60
Purchase #6	$16.76	10.758%	$18.563	$18.56	$18.55	$18.60
Purchase #7	$119.25	11.703%	$133.2058	$133.21	$133.20	$133.20
7 purchase totals =	$940.82		$1,032.0884	$1,032.09	$1,032.10	$1,032.10