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	$191.96	5.453%	$202.4276	$202.43	$202.45	$202.40
Purchase #2	$120.89	11.459%	$134.7428	$134.74	$134.75	$134.70
Purchase #3	$134.88	5.693%	$142.5587	$142.56	$142.55	$142.60
Purchase #4	$136.88	12.309%	$153.7286	$153.73	$153.75	$153.70
Purchase #5	$175.50	9.741%	$192.5955	$192.60	$192.60	$192.60
Purchase #6	$128.82	12.494%	$144.9148	$144.91	$144.90	$144.90
Purchase #7	$123.62	7.254%	$132.5874	$132.59	$132.60	$132.60
7 purchase totals =	$1,012.55		$1,103.5554	$1,103.56	$1,103.60	$1,103.50