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	$59.40	4.193%	$61.8906	$61.89	$61.90	$61.90
Purchase #2	$106.39	3.289%	$109.8892	$109.89	$109.90	$109.90
Purchase #3	$139.74	11.761%	$156.1748	$156.17	$156.15	$156.20
Purchase #4	$238.50	12.318%	$267.8784	$267.88	$267.90	$267.90
Purchase #5	$28.56	3.268%	$29.4933	$29.49	$29.50	$29.50
Purchase #6	$245.47	10.611%	$271.5168	$271.52	$271.50	$271.50
Purchase #7	$122.66	10.223%	$135.1995	$135.20	$135.20	$135.20
7 purchase totals =	$940.72		$1,032.0426	$1,032.04	$1,032.05	$1,032.10