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	$144.81	5.214%	$152.3604	$152.36	$152.35	$152.40
Purchase #2	$131.71	3.714%	$136.6017	$136.60	$136.60	$136.60
Purchase #3	$150.88	5.653%	$159.4092	$159.41	$159.40	$159.40
Purchase #4	$238.95	4.867%	$250.5797	$250.58	$250.60	$250.60
Purchase #5	$244.83	4.350%	$255.4801	$255.48	$255.50	$255.50
Purchase #6	$87.49	3.381%	$90.448	$90.45	$90.45	$90.40
Purchase #7	$123.59	4.777%	$129.4939	$129.49	$129.50	$129.50
7 purchase totals =	$1,122.26		$1,174.3730	$1,174.37	$1,174.40	$1,174.40