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	$172.59	11.552%	$192.5276	$192.53	$192.55	$192.50
Purchase #2	$116.83	9.394%	$127.805	$127.81	$127.80	$127.80
Purchase #3	$183.32	9.112%	$200.0241	$200.02	$200.00	$200.00
Purchase #4	$90.84	11.249%	$101.0586	$101.06	$101.05	$101.10
Purchase #5	$148.56	9.383%	$162.4994	$162.50	$162.50	$162.50
Purchase #6	$86.90	12.547%	$97.8033	$97.80	$97.80	$97.80
Purchase #7	$169.92	9.311%	$185.7413	$185.74	$185.75	$185.70
7 purchase totals =	$968.96		$1,067.4593	$1,067.46	$1,067.45	$1,067.40