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	$144.58	5.145%	$152.0186	$152.02	$152.00	$152.00
Purchase #2	$212.96	8.640%	$231.3597	$231.36	$231.35	$231.40
Purchase #3	$81.98	4.507%	$85.6748	$85.67	$85.65	$85.70
Purchase #4	$64.54	4.298%	$67.3139	$67.31	$67.30	$67.30
Purchase #5	$151.49	9.104%	$165.2816	$165.28	$165.30	$165.30
Purchase #6	$119.79	3.259%	$123.694	$123.69	$123.70	$123.70
Purchase #7	$189.79	13.619%	$215.6375	$215.64	$215.65	$215.60
7 purchase totals =	$965.13		$1,040.9801	$1,040.97	$1,040.95	$1,041.00