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	$126.99	13.825%	$144.5464	$144.55	$144.55	$144.50
Purchase #2	$41.26	9.359%	$45.1215	$45.12	$45.10	$45.10
Purchase #3	$79.79	11.865%	$89.2571	$89.26	$89.25	$89.30
Purchase #4	$131.73	10.539%	$145.613	$145.61	$145.60	$145.60
Purchase #5	$217.33	4.161%	$226.3731	$226.37	$226.35	$226.40
Purchase #6	$170.54	8.869%	$185.6652	$185.67	$185.65	$185.70
Purchase #7	$177.96	4.690%	$186.3063	$186.31	$186.30	$186.30
7 purchase totals =	$945.60		$1,022.8826	$1,022.89	$1,022.80	$1,022.90