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	$226.32	8.633%	$245.8582	$245.86	$245.85	$245.90
Purchase #2	$89.35	13.708%	$101.5981	$101.60	$101.60	$101.60
Purchase #3	$122.70	5.507%	$129.4571	$129.46	$129.45	$129.50
Purchase #4	$217.51	8.104%	$235.137	$235.14	$235.15	$235.10
Purchase #5	$87.99	13.780%	$100.115	$100.12	$100.10	$100.10
Purchase #6	$142.59	6.872%	$152.3888	$152.39	$152.40	$152.40
Purchase #7	$179.53	3.768%	$186.2947	$186.29	$186.30	$186.30
7 purchase totals =	$1,065.99		$1,150.8489	$1,150.86	$1,150.85	$1,150.90