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	$113.38	4.742%	$118.7565	$118.76	$118.75	$118.80
Purchase #2	$95.79	10.510%	$105.8575	$105.86	$105.85	$105.90
Purchase #3	$168.78	7.118%	$180.7938	$180.79	$180.80	$180.80
Purchase #4	$178.47	9.434%	$195.3069	$195.31	$195.30	$195.30
Purchase #5	$84.61	5.488%	$89.2534	$89.25	$89.25	$89.30
Purchase #6	$183.41	13.817%	$208.7518	$208.75	$208.75	$208.80
Purchase #7	$169.77	8.809%	$184.725	$184.73	$184.75	$184.70
7 purchase totals =	$994.21		$1,083.4449	$1,083.45	$1,083.45	$1,083.60