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	$22.57	3.471%	$23.3534	$23.35	$23.35	$23.40
Purchase #2	$225.30	3.645%	$233.5122	$233.51	$233.50	$233.50
Purchase #3	$118.63	7.133%	$127.0919	$127.09	$127.10	$127.10
Purchase #4	$216.46	5.517%	$228.4021	$228.40	$228.40	$228.40
Purchase #5	$80.94	6.588%	$86.2723	$86.27	$86.25	$86.30
Purchase #6	$194.48	7.496%	$209.0582	$209.06	$209.05	$209.10
Purchase #7	$172.44	9.522%	$188.8597	$188.86	$188.85	$188.90
7 purchase totals =	$1,030.82		$1,096.5498	$1,096.54	$1,096.50	$1,096.70