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	$61.55	9.850%	$67.6127	$67.61	$67.60	$67.60
Purchase #2	$211.49	11.439%	$235.6823	$235.68	$235.70	$235.70
Purchase #3	$36.64	3.423%	$37.8942	$37.89	$37.90	$37.90
Purchase #4	$222.86	3.464%	$230.5799	$230.58	$230.60	$230.60
Purchase #5	$205.28	3.220%	$211.89	$211.89	$211.90	$211.90
Purchase #6	$166.79	12.816%	$188.1658	$188.17	$188.15	$188.20
Purchase #7	$169.32	9.757%	$185.8406	$185.84	$185.85	$185.80
7 purchase totals =	$1,073.93		$1,157.6655	$1,157.66	$1,157.70	$1,157.70