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	$154.88	11.651%	$172.9251	$172.93	$172.95	$172.90
Purchase #2	$138.44	9.344%	$151.3758	$151.38	$151.40	$151.40
Purchase #3	$165.44	9.825%	$181.6945	$181.69	$181.70	$181.70
Purchase #4	$39.63	12.184%	$44.4585	$44.46	$44.45	$44.50
Purchase #5	$228.41	5.714%	$241.4613	$241.46	$241.45	$241.50
Purchase #6	$55.27	7.343%	$59.3285	$59.33	$59.35	$59.30
Purchase #7	$101.55	10.663%	$112.3783	$112.38	$112.40	$112.40
7 purchase totals =	$883.62		$963.6220	$963.63	$963.70	$963.70