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	$175.40	11.759%	$196.0253	$196.03	$196.05	$196.00
Purchase #2	$233.63	13.197%	$264.4622	$264.46	$264.45	$264.50
Purchase #3	$112.60	7.864%	$121.4549	$121.45	$121.45	$121.50
Purchase #4	$102.63	11.415%	$114.3452	$114.35	$114.35	$114.30
Purchase #5	$92.64	7.740%	$99.8103	$99.81	$99.80	$99.80
Purchase #6	$181.62	5.465%	$191.5455	$191.55	$191.55	$191.50
Purchase #7	$116.73	5.651%	$123.3264	$123.33	$123.35	$123.30
7 purchase totals =	$1,015.25		$1,110.9698	$1,110.98	$1,111.00	$1,110.90