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	$182.53	7.822%	$196.8075	$196.81	$196.80	$196.80
Purchase #2	$194.63	9.645%	$213.4021	$213.40	$213.40	$213.40
Purchase #3	$162.31	10.156%	$178.7942	$178.79	$178.80	$178.80
Purchase #4	$29.88	11.482%	$33.3108	$33.31	$33.30	$33.30
Purchase #5	$62.45	8.654%	$67.8544	$67.85	$67.85	$67.90
Purchase #6	$148.55	4.106%	$154.6495	$154.65	$154.65	$154.60
Purchase #7	$197.96	8.773%	$215.327	$215.33	$215.35	$215.30
7 purchase totals =	$978.31		$1,060.1455	$1,060.14	$1,060.15	$1,060.10