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	$198.46	7.755%	$213.8506	$213.85	$213.85	$213.90
Purchase #2	$33.40	7.363%	$35.8592	$35.86	$35.85	$35.90
Purchase #3	$73.91	8.608%	$80.2722	$80.27	$80.25	$80.30
Purchase #4	$245.98	5.301%	$259.0194	$259.02	$259.00	$259.00
Purchase #5	$128.72	3.194%	$132.8313	$132.83	$132.85	$132.80
Purchase #6	$159.34	10.633%	$176.2826	$176.28	$176.30	$176.30
Purchase #7	$239.56	12.503%	$269.5122	$269.51	$269.50	$269.50
7 purchase totals =	$1,079.37		$1,167.6275	$1,167.62	$1,167.60	$1,167.70