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	$174.86	12.153%	$196.1107	$196.11	$196.10	$196.10
Purchase #2	$162.29	6.123%	$172.227	$172.23	$172.25	$172.20
Purchase #3	$226.64	6.165%	$240.6124	$240.61	$240.60	$240.60
Purchase #4	$247.26	3.211%	$255.1995	$255.20	$255.20	$255.20
Purchase #5	$186.50	6.642%	$198.8873	$198.89	$198.90	$198.90
Purchase #6	$217.77	8.273%	$235.7861	$235.79	$235.80	$235.80
Purchase #7	$144.36	12.474%	$162.3675	$162.37	$162.35	$162.40
7 purchase totals =	$1,359.68		$1,461.1905	$1,461.20	$1,461.20	$1,461.20