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	$176.59	8.411%	$191.443	$191.44	$191.45	$191.40
Purchase #2	$174.83	5.852%	$185.0611	$185.06	$185.05	$185.10
Purchase #3	$54.52	3.615%	$56.4909	$56.49	$56.50	$56.50
Purchase #4	$65.46	7.317%	$70.2497	$70.25	$70.25	$70.20
Purchase #5	$234.82	11.260%	$261.2607	$261.26	$261.25	$261.30
Purchase #6	$163.31	13.316%	$185.0564	$185.06	$185.05	$185.10
Purchase #7	$93.75	9.279%	$102.4491	$102.45	$102.45	$102.40
7 purchase totals =	$963.28		$1,052.0109	$1,052.01	$1,052.00	$1,052.00