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	$223.67	5.215%	$235.3344	$235.33	$235.35	$235.30
Purchase #2	$68.84	5.450%	$72.5918	$72.59	$72.60	$72.60
Purchase #3	$176.64	11.500%	$196.9536	$196.95	$196.95	$197.00
Purchase #4	$95.98	11.405%	$106.9265	$106.93	$106.95	$106.90
Purchase #5	$104.41	9.392%	$114.2162	$114.22	$114.20	$114.20
Purchase #6	$240.73	11.683%	$268.8545	$268.85	$268.85	$268.90
Purchase #7	$52.78	11.711%	$58.9611	$58.96	$58.95	$59.00
7 purchase totals =	$963.05		$1,053.8381	$1,053.83	$1,053.85	$1,053.90