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	$107.56	9.445%	$117.719	$117.72	$117.70	$117.70
Purchase #2	$94.41	4.242%	$98.4149	$98.41	$98.40	$98.40
Purchase #3	$187.31	4.604%	$195.9338	$195.93	$195.95	$195.90
Purchase #4	$95.83	6.872%	$102.4154	$102.42	$102.40	$102.40
Purchase #5	$179.61	9.177%	$196.0928	$196.09	$196.10	$196.10
Purchase #6	$204.67	9.304%	$223.7125	$223.71	$223.70	$223.70
Purchase #7	$212.87	4.372%	$222.1767	$222.18	$222.20	$222.20
7 purchase totals =	$1,082.26		$1,156.4651	$1,156.46	$1,156.45	$1,156.40