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	$181.36	8.165%	$196.168	$196.17	$196.15	$196.20
Purchase #2	$25.46	11.354%	$28.3507	$28.35	$28.35	$28.40
Purchase #3	$219.74	5.701%	$232.2674	$232.27	$232.25	$232.30
Purchase #4	$145.77	12.821%	$164.4592	$164.46	$164.45	$164.50
Purchase #5	$46.91	9.112%	$51.1844	$51.18	$51.20	$51.20
Purchase #6	$39.27	10.487%	$43.3882	$43.39	$43.40	$43.40
Purchase #7	$242.49	3.476%	$250.919	$250.92	$250.90	$250.90
7 purchase totals =	$901.00		$966.7369	$966.74	$966.70	$966.90