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	$146.33	5.219%	$153.967	$153.97	$153.95	$154.00
Purchase #2	$27.68	11.374%	$30.8283	$30.83	$30.85	$30.80
Purchase #3	$187.92	4.602%	$196.5681	$196.57	$196.55	$196.60
Purchase #4	$55.30	7.206%	$59.2849	$59.28	$59.30	$59.30
Purchase #5	$83.59	12.772%	$94.2661	$94.27	$94.25	$94.30
Purchase #6	$228.41	7.151%	$244.7436	$244.74	$244.75	$244.70
Purchase #7	$84.32	13.782%	$95.941	$95.94	$95.95	$95.90
7 purchase totals =	$813.55		$875.5990	$875.60	$875.60	$875.60