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	$175.89	13.446%	$199.5402	$199.54	$199.55	$199.50
Purchase #2	$176.57	12.157%	$198.0356	$198.04	$198.05	$198.00
Purchase #3	$36.61	8.847%	$39.8489	$39.85	$39.85	$39.80
Purchase #4	$141.82	6.525%	$151.0738	$151.07	$151.05	$151.10
Purchase #5	$40.90	6.377%	$43.5082	$43.51	$43.50	$43.50
Purchase #6	$151.50	10.278%	$167.0712	$167.07	$167.05	$167.10
Purchase #7	$231.83	6.173%	$246.1409	$246.14	$246.15	$246.10
7 purchase totals =	$955.12		$1,045.2188	$1,045.22	$1,045.20	$1,045.10