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	$162.89	7.413%	$174.965	$174.97	$174.95	$175.00
Purchase #2	$39.38	3.736%	$40.8512	$40.85	$40.85	$40.90
Purchase #3	$222.56	4.814%	$233.274	$233.27	$233.25	$233.30
Purchase #4	$128.93	3.152%	$132.9939	$132.99	$133.00	$133.00
Purchase #5	$136.38	10.439%	$150.6167	$150.62	$150.60	$150.60
Purchase #6	$191.91	10.633%	$212.3158	$212.32	$212.30	$212.30
Purchase #7	$153.34	10.810%	$169.9161	$169.92	$169.90	$169.90
7 purchase totals =	$1,035.39		$1,114.9327	$1,114.94	$1,114.85	$1,115.00