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	$67.47	5.833%	$71.4055	$71.41	$71.40	$71.40
Purchase #2	$128.44	6.541%	$136.8413	$136.84	$136.85	$136.80
Purchase #3	$80.61	3.724%	$83.6119	$83.61	$83.60	$83.60
Purchase #4	$182.94	5.658%	$193.2907	$193.29	$193.30	$193.30
Purchase #5	$150.29	12.156%	$168.5593	$168.56	$168.55	$168.60
Purchase #6	$178.81	3.774%	$185.5583	$185.56	$185.55	$185.60
Purchase #7	$191.91	11.163%	$213.3329	$213.33	$213.35	$213.30
7 purchase totals =	$980.47		$1,052.5999	$1,052.60	$1,052.60	$1,052.60