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	$146.86	4.776%	$153.874	$153.87	$153.85	$153.90
Purchase #2	$109.32	8.417%	$118.5215	$118.52	$118.50	$118.50
Purchase #3	$110.48	7.581%	$118.8555	$118.86	$118.85	$118.90
Purchase #4	$106.52	12.206%	$119.5218	$119.52	$119.50	$119.50
Purchase #5	$174.84	4.516%	$182.7358	$182.74	$182.75	$182.70
Purchase #6	$192.32	7.847%	$207.4114	$207.41	$207.40	$207.40
Purchase #7	$122.45	7.465%	$131.5909	$131.59	$131.60	$131.60
7 purchase totals =	$962.79		$1,032.5109	$1,032.51	$1,032.45	$1,032.50