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	$222.31	5.499%	$234.5348	$234.53	$234.55	$234.50
Purchase #2	$54.47	12.299%	$61.1693	$61.17	$61.15	$61.20
Purchase #3	$96.95	3.488%	$100.3316	$100.33	$100.35	$100.30
Purchase #4	$64.98	12.285%	$72.9628	$72.96	$72.95	$73.00
Purchase #5	$231.76	13.195%	$262.3407	$262.34	$262.35	$262.30
Purchase #6	$69.83	12.106%	$78.2836	$78.28	$78.30	$78.30
Purchase #7	$217.42	3.626%	$225.3036	$225.30	$225.30	$225.30
7 purchase totals =	$957.72		$1,034.9264	$1,034.91	$1,034.95	$1,034.90