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	$202.61	4.553%	$211.8348	$211.83	$211.85	$211.80
Purchase #2	$119.30	7.499%	$128.2463	$128.25	$128.25	$128.20
Purchase #3	$159.65	7.535%	$171.6796	$171.68	$171.70	$171.70
Purchase #4	$234.79	5.401%	$247.471	$247.47	$247.45	$247.50
Purchase #5	$98.45	9.543%	$107.8451	$107.85	$107.85	$107.80
Purchase #6	$128.77	10.480%	$142.2651	$142.27	$142.25	$142.30
Purchase #7	$78.55	10.710%	$86.9627	$86.96	$86.95	$87.00
7 purchase totals =	$1,022.12		$1,096.3046	$1,096.31	$1,096.30	$1,096.30