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	$42.68	4.814%	$44.7346	$44.73	$44.75	$44.70
Purchase #2	$168.28	3.478%	$174.1328	$174.13	$174.15	$174.10
Purchase #3	$156.92	3.289%	$162.0811	$162.08	$162.10	$162.10
Purchase #4	$235.63	8.273%	$255.1237	$255.12	$255.10	$255.10
Purchase #5	$69.63	3.783%	$72.2641	$72.26	$72.25	$72.30
Purchase #6	$137.38	13.733%	$156.2464	$156.25	$156.25	$156.20
Purchase #7	$216.88	7.619%	$233.4041	$233.40	$233.40	$233.40
7 purchase totals =	$1,027.40		$1,097.9868	$1,097.97	$1,098.00	$1,097.90