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	$147.91	5.284%	$155.7256	$155.73	$155.75	$155.70
Purchase #2	$157.35	5.637%	$166.2198	$166.22	$166.20	$166.20
Purchase #3	$184.62	7.445%	$198.365	$198.37	$198.35	$198.40
Purchase #4	$27.52	4.228%	$28.6835	$28.68	$28.70	$28.70
Purchase #5	$151.50	4.469%	$158.2705	$158.27	$158.25	$158.30
Purchase #6	$159.64	4.626%	$167.0249	$167.02	$167.00	$167.00
Purchase #7	$140.46	3.146%	$144.8789	$144.88	$144.90	$144.90
7 purchase totals =	$969.00		$1,019.1682	$1,019.17	$1,019.15	$1,019.20