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	$124.55	13.219%	$141.0143	$141.01	$141.00	$141.00
Purchase #2	$133.40	9.108%	$145.5501	$145.55	$145.55	$145.60
Purchase #3	$59.76	6.601%	$63.7048	$63.70	$63.70	$63.70
Purchase #4	$159.92	11.501%	$178.3124	$178.31	$178.30	$178.30
Purchase #5	$250.90	9.775%	$275.4255	$275.43	$275.45	$275.40
Purchase #6	$140.41	11.418%	$156.442	$156.44	$156.45	$156.40
Purchase #7	$166.75	12.201%	$187.0952	$187.10	$187.10	$187.10
7 purchase totals =	$1,035.69		$1,147.5443	$1,147.54	$1,147.55	$1,147.50