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	$99.49	13.535%	$112.956	$112.96	$112.95	$113.00
Purchase #2	$133.66	9.792%	$146.748	$146.75	$146.75	$146.70
Purchase #3	$187.47	7.167%	$200.906	$200.91	$200.90	$200.90
Purchase #4	$37.29	5.473%	$39.3309	$39.33	$39.35	$39.30
Purchase #5	$150.76	9.147%	$164.55	$164.55	$164.55	$164.60
Purchase #6	$218.25	7.192%	$233.9465	$233.95	$233.95	$233.90
Purchase #7	$226.63	7.123%	$242.7729	$242.77	$242.75	$242.80
7 purchase totals =	$1,053.55		$1,141.2103	$1,141.22	$1,141.20	$1,141.20