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	$101.60	9.785%	$111.5416	$111.54	$111.55	$111.50
Purchase #2	$11.35	10.165%	$12.5037	$12.50	$12.50	$12.50
Purchase #3	$233.74	13.159%	$264.4978	$264.50	$264.50	$264.50
Purchase #4	$244.45	13.417%	$277.2479	$277.25	$277.25	$277.20
Purchase #5	$163.63	13.476%	$185.6808	$185.68	$185.70	$185.70
Purchase #6	$181.41	8.239%	$196.3564	$196.36	$196.35	$196.40
Purchase #7	$61.50	3.628%	$63.7312	$63.73	$63.75	$63.70
7 purchase totals =	$997.68		$1,111.5594	$1,111.56	$1,111.60	$1,111.50