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	$194.29	11.196%	$216.0427	$216.04	$216.05	$216.00
Purchase #2	$15.82	10.392%	$17.464	$17.46	$17.45	$17.50
Purchase #3	$72.31	8.596%	$78.5258	$78.53	$78.55	$78.50
Purchase #4	$101.54	7.409%	$109.0631	$109.06	$109.05	$109.10
Purchase #5	$55.66	10.205%	$61.3401	$61.34	$61.35	$61.30
Purchase #6	$101.49	13.262%	$114.9496	$114.95	$114.95	$114.90
Purchase #7	$89.77	7.307%	$96.3295	$96.33	$96.35	$96.30
7 purchase totals =	$630.88		$693.7148	$693.71	$693.75	$693.60