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	$94.51	7.325%	$101.4329	$101.43	$101.45	$101.40
Purchase #2	$167.69	5.205%	$176.4183	$176.42	$176.40	$176.40
Purchase #3	$152.57	9.107%	$166.4645	$166.46	$166.45	$166.50
Purchase #4	$29.51	10.127%	$32.4985	$32.50	$32.50	$32.50
Purchase #5	$139.82	8.797%	$152.12	$152.12	$152.10	$152.10
Purchase #6	$191.83	12.590%	$215.9814	$215.98	$216.00	$216.00
Purchase #7	$160.27	11.454%	$178.6273	$178.63	$178.65	$178.60
7 purchase totals =	$936.20		$1,023.5429	$1,023.54	$1,023.55	$1,023.50