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	$229.89	3.468%	$237.8626	$237.86	$237.85	$237.90
Purchase #2	$112.92	5.824%	$119.4965	$119.50	$119.50	$119.50
Purchase #3	$92.97	9.863%	$102.1396	$102.14	$102.15	$102.10
Purchase #4	$158.62	13.674%	$180.3097	$180.31	$180.30	$180.30
Purchase #5	$159.89	9.113%	$174.4608	$174.46	$174.45	$174.50
Purchase #6	$180.63	8.815%	$196.5525	$196.55	$196.55	$196.60
Purchase #7	$247.87	4.427%	$258.8432	$258.84	$258.85	$258.80
7 purchase totals =	$1,182.79		$1,269.6649	$1,269.66	$1,269.65	$1,269.70