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	$145.90	4.564%	$152.5589	$152.56	$152.55	$152.60
Purchase #2	$164.36	10.694%	$181.9367	$181.94	$181.95	$181.90
Purchase #3	$87.94	4.826%	$92.184	$92.18	$92.20	$92.20
Purchase #4	$180.66	3.790%	$187.507	$187.51	$187.50	$187.50
Purchase #5	$203.94	3.873%	$211.8386	$211.84	$211.85	$211.80
Purchase #6	$78.45	5.231%	$82.5537	$82.55	$82.55	$82.60
Purchase #7	$214.48	4.339%	$223.7863	$223.79	$223.80	$223.80
7 purchase totals =	$1,075.73		$1,132.3652	$1,132.37	$1,132.40	$1,132.40