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	$124.72	4.107%	$129.8423	$129.84	$129.85	$129.80
Purchase #2	$17.28	3.685%	$17.9168	$17.92	$17.90	$17.90
Purchase #3	$82.71	7.511%	$88.9223	$88.92	$88.90	$88.90
Purchase #4	$44.57	4.484%	$46.5685	$46.57	$46.55	$46.60
Purchase #5	$164.94	13.681%	$187.5054	$187.51	$187.50	$187.50
Purchase #6	$37.69	13.835%	$42.9044	$42.90	$42.90	$42.90
Purchase #7	$200.43	5.722%	$211.8986	$211.90	$211.90	$211.90
7 purchase totals =	$672.34		$725.5583	$725.56	$725.50	$725.50