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	$196.97	9.284%	$215.2567	$215.26	$215.25	$215.30
Purchase #2	$164.28	13.255%	$186.0553	$186.06	$186.05	$186.10
Purchase #3	$150.30	5.611%	$158.7333	$158.73	$158.75	$158.70
Purchase #4	$124.96	11.760%	$139.6553	$139.66	$139.65	$139.70
Purchase #5	$206.29	7.746%	$222.2692	$222.27	$222.25	$222.30
Purchase #6	$217.95	12.766%	$245.7735	$245.77	$245.75	$245.80
Purchase #7	$118.25	12.660%	$133.2205	$133.22	$133.20	$133.20
7 purchase totals =	$1,179.00		$1,300.9638	$1,300.97	$1,300.90	$1,301.10