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	$179.39	6.708%	$191.4235	$191.42	$191.40	$191.40
Purchase #2	$196.90	4.850%	$206.4497	$206.45	$206.45	$206.40
Purchase #3	$17.59	9.472%	$19.2561	$19.26	$19.25	$19.30
Purchase #4	$240.54	4.148%	$250.5176	$250.52	$250.50	$250.50
Purchase #5	$108.50	4.333%	$113.2013	$113.20	$113.20	$113.20
Purchase #6	$165.64	4.121%	$172.466	$172.47	$172.45	$172.50
Purchase #7	$93.52	7.516%	$100.549	$100.55	$100.55	$100.50
7 purchase totals =	$1,002.08		$1,053.8632	$1,053.87	$1,053.80	$1,053.80