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	$119.56	5.352%	$125.9589	$125.96	$125.95	$126.00
Purchase #2	$123.52	10.824%	$136.8898	$136.89	$136.90	$136.90
Purchase #3	$120.59	11.430%	$134.3734	$134.37	$134.35	$134.40
Purchase #4	$196.85	10.124%	$216.7791	$216.78	$216.80	$216.80
Purchase #5	$43.27	9.315%	$47.3006	$47.30	$47.30	$47.30
Purchase #6	$67.43	5.357%	$71.0422	$71.04	$71.05	$71.00
Purchase #7	$85.32	5.431%	$89.9537	$89.95	$89.95	$90.00
7 purchase totals =	$756.54		$822.2977	$822.29	$822.30	$822.40