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	$168.37	7.398%	$180.826	$180.83	$180.85	$180.80
Purchase #2	$115.88	6.701%	$123.6451	$123.65	$123.65	$123.60
Purchase #3	$101.74	13.438%	$115.4118	$115.41	$115.40	$115.40
Purchase #4	$135.99	5.103%	$142.9296	$142.93	$142.95	$142.90
Purchase #5	$132.67	11.477%	$147.8965	$147.90	$147.90	$147.90
Purchase #6	$203.96	5.401%	$214.9759	$214.98	$215.00	$215.00
Purchase #7	$174.73	6.330%	$185.7904	$185.79	$185.80	$185.80
7 purchase totals =	$1,033.34		$1,111.4753	$1,111.49	$1,111.55	$1,111.40