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	$190.65	3.308%	$196.9567	$196.96	$196.95	$197.00
Purchase #2	$231.35	8.365%	$250.7024	$250.70	$250.70	$250.70
Purchase #3	$30.86	8.778%	$33.5689	$33.57	$33.55	$33.60
Purchase #4	$166.28	3.456%	$172.0266	$172.03	$172.05	$172.00
Purchase #5	$103.56	10.655%	$114.5943	$114.59	$114.60	$114.60
Purchase #6	$146.35	12.868%	$165.1823	$165.18	$165.20	$165.20
Purchase #7	$224.69	7.196%	$240.8587	$240.86	$240.85	$240.90
7 purchase totals =	$1,093.74		$1,173.8899	$1,173.89	$1,173.90	$1,174.00