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	$191.95	3.426%	$198.5262	$198.53	$198.55	$198.50
Purchase #2	$192.89	12.142%	$216.3107	$216.31	$216.30	$216.30
Purchase #3	$96.53	4.521%	$100.8941	$100.89	$100.90	$100.90
Purchase #4	$127.41	6.602%	$135.8216	$135.82	$135.80	$135.80
Purchase #5	$136.59	5.701%	$144.377	$144.38	$144.40	$144.40
Purchase #6	$83.82	13.750%	$95.3453	$95.35	$95.35	$95.30
Purchase #7	$209.91	7.191%	$225.0046	$225.00	$225.00	$225.00
7 purchase totals =	$1,039.10		$1,116.2795	$1,116.28	$1,116.30	$1,116.20