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	$213.34	10.590%	$235.9327	$235.93	$235.95	$235.90
Purchase #2	$20.76	3.318%	$21.4488	$21.45	$21.45	$21.40
Purchase #3	$171.53	6.588%	$182.8304	$182.83	$182.85	$182.80
Purchase #4	$135.77	7.141%	$145.4653	$145.47	$145.45	$145.50
Purchase #5	$211.54	5.780%	$223.767	$223.77	$223.75	$223.80
Purchase #6	$229.69	12.109%	$257.5032	$257.50	$257.50	$257.50
Purchase #7	$114.67	12.592%	$129.1092	$129.11	$129.10	$129.10
7 purchase totals =	$1,097.30		$1,196.0566	$1,196.06	$1,196.05	$1,196.00