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	$202.25	3.219%	$208.7604	$208.76	$208.75	$208.80
Purchase #2	$70.51	6.312%	$74.9606	$74.96	$74.95	$75.00
Purchase #3	$42.72	13.441%	$48.462	$48.46	$48.45	$48.50
Purchase #4	$206.39	6.524%	$219.8549	$219.85	$219.85	$219.90
Purchase #5	$228.41	7.529%	$245.607	$245.61	$245.60	$245.60
Purchase #6	$198.92	9.669%	$218.1536	$218.15	$218.15	$218.20
Purchase #7	$40.73	10.560%	$45.0311	$45.03	$45.05	$45.00
7 purchase totals =	$989.93		$1,060.8296	$1,060.82	$1,060.80	$1,061.00