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	$176.33	10.764%	$195.3102	$195.31	$195.30	$195.30
Purchase #2	$161.56	10.823%	$179.0456	$179.05	$179.05	$179.00
Purchase #3	$182.86	6.642%	$195.0056	$195.01	$195.00	$195.00
Purchase #4	$112.50	6.640%	$119.97	$119.97	$119.95	$120.00
Purchase #5	$230.57	5.620%	$243.528	$243.53	$243.55	$243.50
Purchase #6	$69.75	12.859%	$78.7192	$78.72	$78.70	$78.70
Purchase #7	$55.60	7.180%	$59.5921	$59.59	$59.60	$59.60
7 purchase totals =	$989.17		$1,071.1707	$1,071.18	$1,071.15	$1,071.10